From beb90d57561953837b42828293f97b57e0aed3f7 Mon Sep 17 00:00:00 2001
From: Jef Roosens <roosensjef@gmail.com>
Date: Thu, 12 Jan 2023 12:26:12 +0100
Subject: [PATCH] refactor: link libvieter; remove cron code & daemon

This giant commit removes the old cron daemon & parser, replacing the
latter with a C implementation that will now be maintained in a separate
C library that gets developed independently. This commit lays the
groundwork for implementing features of Vieter in C where possible.
---
 .clang-format                               |   4 +
 .editorconfig                               |   3 +-
 .gitignore                                  |   2 +-
 .gitmodules                                 |   3 +
 CHANGELOG.md                                |   4 +
 Makefile                                    |  25 +-
 src/build/queue.v                           |  26 +-
 src/console/schedule/schedule.v             |   6 +-
 src/console/targets/targets.v               |   4 +-
 src/cron/cli.v                              |  32 ---
 src/cron/cron.v                             |  33 ---
 src/cron/daemon/build.v                     | 115 --------
 src/cron/daemon/daemon.v                    | 274 --------------------
 src/cron/daemon/log.v                       |  36 ---
 src/cron/expression.c.v                     |  99 +++++++
 src/cron/expression.v                       |  73 ++++++
 src/cron/expression/expression.v            | 136 ----------
 src/cron/expression/expression_parse.v      | 146 -----------
 src/cron/expression/expression_parse_test.v |  89 -------
 src/cron/{expression => }/expression_test.v |  17 +-
 src/cron/parse_test.v                       |  42 +++
 src/libvieter                               |   1 +
 src/main.v                                  |   2 -
 src/server/log_removal.v                    |  15 +-
 src/server/server.v                         |   6 +-
 vieter.toml                                 |   1 +
 26 files changed, 278 insertions(+), 916 deletions(-)
 create mode 100644 .clang-format
 delete mode 100644 src/cron/cli.v
 delete mode 100644 src/cron/cron.v
 delete mode 100644 src/cron/daemon/build.v
 delete mode 100644 src/cron/daemon/daemon.v
 delete mode 100644 src/cron/daemon/log.v
 create mode 100644 src/cron/expression.c.v
 create mode 100644 src/cron/expression.v
 delete mode 100644 src/cron/expression/expression.v
 delete mode 100644 src/cron/expression/expression_parse.v
 delete mode 100644 src/cron/expression/expression_parse_test.v
 rename src/cron/{expression => }/expression_test.v (56%)
 create mode 100644 src/cron/parse_test.v
 create mode 160000 src/libvieter

diff --git a/.clang-format b/.clang-format
new file mode 100644
index 0000000..2e6afb4
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1,4 @@
+# To stay consistent with the V formatting style, we use tabs
+UseTab: Always
+IndentWidth: 4
+TabWidth: 4
diff --git a/.editorconfig b/.editorconfig
index e23a3c7..e9c1e63 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -5,6 +5,5 @@ root = true
 end_of_line = lf
 insert_final_newline = true
 
-[*.v]
-# vfmt wants it :(
+[*.{v,c,h}]
 indent_style = tab
diff --git a/.gitignore b/.gitignore
index aaec9ef..daeb3d3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,4 @@
-*.c
+vieter.c
 /data/
 
 # Build artifacts
diff --git a/.gitmodules b/.gitmodules
index 47029a0..24af818 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,6 @@
 [submodule "docs/themes/hugo-book"]
 	path = docs/themes/hugo-book
 	url = https://github.com/alex-shpak/hugo-book
+[submodule "src/libvieter"]
+	path = src/libvieter
+	url = https://git.rustybever.be/vieter-v/libvieter
diff --git a/CHANGELOG.md b/CHANGELOG.md
index be5f445..6b1e583 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Search in list of targets using API & CLI
 * Allow filtering targets by arch value
 
+### Changed
+
+* Rewrote cron expression logic in C
+
 ## [0.5.0](https://git.rustybever.be/vieter-v/vieter/src/tag/0.5.0)
 
 ### Added
diff --git a/Makefile b/Makefile
index 4bd1edc..2f6029e 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 # =====CONFIG=====
 SRC_DIR := src
-SOURCES != find '$(SRC_DIR)' -iname '*.v'
+SRCS != find '$(SRC_DIR)' -iname '*.v'
 
 V_PATH ?= v
 V := $(V_PATH) -showcc -gc boehm -W -d use_openssl -skip-unused
@@ -9,8 +9,12 @@ all: vieter
 
 
 # =====COMPILATION=====
+.PHONY: libvieter
+libvieter:
+	CFLAGS='-O3' make -C '$(SRC_DIR)/libvieter'
+
 # Regular binary
-vieter: $(SOURCES)
+vieter: $(SOURCES) libvieter
 	$(V) -g -o vieter $(SRC_DIR)
 
 # Debug build using gcc
@@ -18,7 +22,7 @@ vieter: $(SOURCES)
 # multi-threaded and causes issues when running vieter inside gdb.
 .PHONY: debug
 debug: dvieter
-dvieter: $(SOURCES)
+dvieter: $(SOURCES) libvieter
 	$(V_PATH) -showcc -keepc -cg -o dvieter $(SRC_DIR)
 
 # Run the debug build inside gdb
@@ -29,12 +33,12 @@ gdb: dvieter
 # Optimised production build
 .PHONY: prod
 prod: pvieter
-pvieter: $(SOURCES)
+pvieter: $(SOURCES) libvieter
 	$(V) -o pvieter -prod $(SRC_DIR)
 
 # Only generate C code
 .PHONY: c
-c: $(SOURCES)
+c: $(SOURCES) libvieter
 	$(V) -o vieter.c $(SRC_DIR)
 
 
@@ -67,6 +71,7 @@ man: vieter
 
 
 # =====OTHER=====
+# Linting
 .PHONY: lint
 lint:
 	$(V) fmt -verify $(SRC_DIR)
@@ -74,18 +79,24 @@ lint:
 	$(V_PATH) missdoc -p $(SRC_DIR)
 	@ [ $$($(V_PATH) missdoc -p $(SRC_DIR) | wc -l) = 0 ]
 
-# Format the V codebase
+
+# Formatting
 .PHONY: fmt
 fmt:
 	$(V) fmt -w $(SRC_DIR)
 
+
+# Testing
 .PHONY: test
 test:
-	$(V) test $(SRC_DIR)
+	$(V) -g test $(SRC_DIR)
 
+
+# Cleaning
 .PHONY: clean
 clean:
 	rm -rf 'data' 'vieter' 'dvieter' 'pvieter' 'vieter.c' 'pkg' 'src/vieter' *.pkg.tar.zst 'suvieter' 'afvieter' '$(SRC_DIR)/_docs' 'docs/public'
+	make -C '$(SRC_DIR)/libvieter' clean
 
 
 # =====EXPERIMENTAL=====
diff --git a/src/build/queue.v b/src/build/queue.v
index e74529c..abd4ec6 100644
--- a/src/build/queue.v
+++ b/src/build/queue.v
@@ -1,7 +1,7 @@
 module build
 
 import models { BuildConfig, Target }
-import cron.expression { CronExpression, parse_expression }
+import cron
 import time
 import datatypes { MinHeap }
 import util
@@ -13,7 +13,7 @@ pub mut:
 	// Next timestamp from which point this job is allowed to be executed
 	timestamp time.Time
 	// Required for calculating next timestamp after having pop'ed a job
-	ce CronExpression
+	ce &cron.Expression = unsafe { nil }
 	// Actual build config sent to the agent
 	config BuildConfig
 	// Whether this is a one-time job
@@ -30,7 +30,7 @@ fn (r1 BuildJob) < (r2 BuildJob) bool {
 // for each architecture. Agents receive jobs from this queue.
 pub struct BuildJobQueue {
 	// Schedule to use for targets without explicitely defined cron expression
-	default_schedule CronExpression
+	default_schedule &cron.Expression
 	// Base image to use for targets without defined base image
 	default_base_image string
 mut:
@@ -44,9 +44,9 @@ mut:
 }
 
 // new_job_queue initializes a new job queue
-pub fn new_job_queue(default_schedule CronExpression, default_base_image string) BuildJobQueue {
+pub fn new_job_queue(default_schedule &cron.Expression, default_base_image string) BuildJobQueue {
 	return BuildJobQueue{
-		default_schedule: default_schedule
+		default_schedule: unsafe { default_schedule }
 		default_base_image: default_base_image
 		invalidated: map[int]time.Time{}
 	}
@@ -85,14 +85,14 @@ pub fn (mut q BuildJobQueue) insert(input InsertConfig) ! {
 
 		if !input.now {
 			ce := if input.target.schedule != '' {
-				parse_expression(input.target.schedule) or {
+				cron.parse_expression(input.target.schedule) or {
 					return error("Error while parsing cron expression '$input.target.schedule' (id $input.target.id): $err.msg()")
 				}
 			} else {
 				q.default_schedule
 			}
 
-			job.timestamp = ce.next_from_now()!
+			job.timestamp = ce.next_from_now()
 			job.ce = ce
 		} else {
 			job.timestamp = time.now()
@@ -105,8 +105,8 @@ pub fn (mut q BuildJobQueue) insert(input InsertConfig) ! {
 // reschedule the given job by calculating the next timestamp and re-adding it
 // to its respective queue. This function is called by the pop functions
 // *after* having pop'ed the job.
-fn (mut q BuildJobQueue) reschedule(job BuildJob, arch string) ! {
-	new_timestamp := job.ce.next_from_now()!
+fn (mut q BuildJobQueue) reschedule(job BuildJob, arch string) {
+	new_timestamp := job.ce.next_from_now()
 
 	new_job := BuildJob{
 		...job
@@ -168,10 +168,7 @@ pub fn (mut q BuildJobQueue) pop(arch string) ?BuildJob {
 			job = q.queues[arch].pop()?
 
 			if !job.single {
-				// TODO how do we handle this properly? Is it even possible for a
-				// cron expression to not return a next time if it's already been
-				// used before?
-				q.reschedule(job, arch) or {}
+				q.reschedule(job, arch)
 			}
 
 			return job
@@ -198,8 +195,7 @@ pub fn (mut q BuildJobQueue) pop_n(arch string, n int) []BuildJob {
 				job = q.queues[arch].pop() or { break }
 
 				if !job.single {
-					// TODO idem
-					q.reschedule(job, arch) or {}
+					q.reschedule(job, arch)
 				}
 
 				out << job
diff --git a/src/console/schedule/schedule.v b/src/console/schedule/schedule.v
index 7ce0516..ceabf24 100644
--- a/src/console/schedule/schedule.v
+++ b/src/console/schedule/schedule.v
@@ -1,7 +1,7 @@
 module schedule
 
 import cli
-import cron.expression { parse_expression }
+import cron
 import time
 
 // cmd returns the cli submodule for previewing a cron schedule.
@@ -19,10 +19,10 @@ pub fn cmd() cli.Command {
 			},
 		]
 		execute: fn (cmd cli.Command) ! {
-			ce := parse_expression(cmd.args.join(' '))!
+			ce := cron.parse_expression(cmd.args.join(' '))!
 			count := cmd.flags.get_int('count')!
 
-			for t in ce.next_n(time.now(), count)! {
+			for t in ce.next_n(time.now(), count) {
 				println(t)
 			}
 		}
diff --git a/src/console/targets/targets.v b/src/console/targets/targets.v
index 6152a53..709c196 100644
--- a/src/console/targets/targets.v
+++ b/src/console/targets/targets.v
@@ -2,7 +2,7 @@ module targets
 
 import cli
 import conf as vconf
-import cron.expression { parse_expression }
+import cron
 import client { NewTarget }
 import console
 import models { TargetFilter }
@@ -295,7 +295,7 @@ fn patch(conf Config, id string, params map[string]string) ! {
 	// We check the cron expression first because it's useless to send an
 	// invalid one to the server.
 	if 'schedule' in params && params['schedule'] != '' {
-		parse_expression(params['schedule']) or {
+		cron.parse_expression(params['schedule']) or {
 			return error('Invalid cron expression: $err.msg()')
 		}
 	}
diff --git a/src/cron/cli.v b/src/cron/cli.v
deleted file mode 100644
index 16a3537..0000000
--- a/src/cron/cli.v
+++ /dev/null
@@ -1,32 +0,0 @@
-module cron
-
-import cli
-import conf as vconf
-
-struct Config {
-pub:
-	log_level               string = 'WARN'
-	api_key                 string
-	address                 string
-	data_dir                string
-	base_image              string = 'archlinux:base-devel'
-	max_concurrent_builds   int    = 1
-	api_update_frequency    int    = 15
-	image_rebuild_frequency int    = 1440
-	// Replicates the behavior of the original cron system
-	global_schedule string = '0 3'
-}
-
-// cmd returns the cli module that handles the cron daemon.
-pub fn cmd() cli.Command {
-	return cli.Command{
-		name: 'cron'
-		description: 'Start the cron service that periodically runs builds.'
-		execute: fn (cmd cli.Command) ! {
-			config_file := cmd.flags.get_string('config-file')!
-			conf := vconf.load<Config>(prefix: 'VIETER_', default_path: config_file)!
-
-			cron(conf)!
-		}
-	}
-}
diff --git a/src/cron/cron.v b/src/cron/cron.v
deleted file mode 100644
index f1d6b7b..0000000
--- a/src/cron/cron.v
+++ /dev/null
@@ -1,33 +0,0 @@
-module cron
-
-import log
-import cron.daemon
-import cron.expression
-import os
-
-const log_file_name = 'vieter.cron.log'
-
-// cron starts a cron daemon & starts periodically scheduling builds.
-pub fn cron(conf Config) ! {
-	// Configure logger
-	log_level := log.level_from_tag(conf.log_level) or {
-		return error('Invalid log level. The allowed values are FATAL, ERROR, WARN, INFO & DEBUG.')
-	}
-
-	mut logger := log.Log{
-		level: log_level
-	}
-
-	log_file := os.join_path_single(conf.data_dir, cron.log_file_name)
-	logger.set_full_logpath(log_file)
-	logger.log_to_console_too()
-
-	ce := expression.parse_expression(conf.global_schedule) or {
-		return error('Error while parsing global cron expression: $err.msg()')
-	}
-
-	mut d := daemon.init_daemon(logger, conf.address, conf.api_key, conf.base_image, ce,
-		conf.max_concurrent_builds, conf.api_update_frequency, conf.image_rebuild_frequency)!
-
-	d.run()
-}
diff --git a/src/cron/daemon/build.v b/src/cron/daemon/build.v
deleted file mode 100644
index 42edc92..0000000
--- a/src/cron/daemon/build.v
+++ /dev/null
@@ -1,115 +0,0 @@
-module daemon
-
-import time
-import sync.stdatomic
-import build
-import os
-
-const (
-	build_empty   = 0
-	build_running = 1
-	build_done    = 2
-)
-
-// clean_finished_builds removes finished builds from the build slots & returns
-// them.
-fn (mut d Daemon) clean_finished_builds() []ScheduledBuild {
-	mut out := []ScheduledBuild{}
-
-	for i in 0 .. d.atomics.len {
-		if stdatomic.load_u64(&d.atomics[i]) == daemon.build_done {
-			stdatomic.store_u64(&d.atomics[i], daemon.build_empty)
-			out << d.builds[i]
-		}
-	}
-
-	return out
-}
-
-// update_builds starts as many builds as possible.
-fn (mut d Daemon) start_new_builds() {
-	now := time.now()
-
-	for d.queue.len() > 0 {
-		elem := d.queue.peek() or {
-			d.lerror("queue.peek() unexpectedly returned an error. This shouldn't happen.")
-
-			break
-		}
-
-		if elem.timestamp < now {
-			sb := d.queue.pop() or {
-				d.lerror("queue.pop() unexpectedly returned an error. This shouldn't happen.")
-
-				break
-			}
-
-			// If this build couldn't be scheduled, no more will be possible.
-			if !d.start_build(sb) {
-				d.queue.insert(sb)
-				break
-			}
-		} else {
-			break
-		}
-	}
-}
-
-// start_build starts a build for the given ScheduledBuild object.
-fn (mut d Daemon) start_build(sb ScheduledBuild) bool {
-	for i in 0 .. d.atomics.len {
-		if stdatomic.load_u64(&d.atomics[i]) == daemon.build_empty {
-			stdatomic.store_u64(&d.atomics[i], daemon.build_running)
-			d.builds[i] = sb
-
-			go d.run_build(i, sb)
-
-			return true
-		}
-	}
-
-	return false
-}
-
-// run_build actually starts the build process for a given target.
-fn (mut d Daemon) run_build(build_index int, sb ScheduledBuild) {
-	d.linfo('started build: $sb.target.url -> $sb.target.repo')
-
-	// 0 means success, 1 means failure
-	mut status := 0
-
-	res := build.build_target(d.client.address, d.client.api_key, d.builder_images.last(),
-		&sb.target, false) or {
-		d.ldebug('build_target error: $err.msg()')
-		status = 1
-
-		build.BuildResult{}
-	}
-
-	if status == 0 {
-		d.linfo('finished build: $sb.target.url -> $sb.target.repo; uploading logs...')
-
-		build_arch := os.uname().machine
-		d.client.add_build_log(sb.target.id, res.start_time, res.end_time, build_arch,
-			res.exit_code, res.logs) or {
-			d.lerror('Failed to upload logs for build: $sb.target.url -> $sb.target.repo')
-		}
-	} else {
-		d.linfo('an error occured during build: $sb.target.url -> $sb.target.repo')
-	}
-
-	stdatomic.store_u64(&d.atomics[build_index], daemon.build_done)
-}
-
-// current_build_count returns how many builds are currently running.
-fn (mut d Daemon) current_build_count() int {
-	mut res := 0
-
-	for i in 0 .. d.atomics.len {
-		if stdatomic.load_u64(&d.atomics[i]) == daemon.build_running {
-			res += 1
-		}
-	}
-
-	return res
-}
diff --git a/src/cron/daemon/daemon.v b/src/cron/daemon/daemon.v
deleted file mode 100644
index b94dab8..0000000
--- a/src/cron/daemon/daemon.v
+++ /dev/null
@@ -1,274 +0,0 @@
-module daemon
-
-import time
-import log
-import datatypes { MinHeap }
-import cron.expression { CronExpression, parse_expression }
-import math
-import build
-import docker
-import os
-import client
-import models { Target }
-
-const (
-	// How many seconds to wait before retrying to update API if failed
-	api_update_retry_timeout        = 5
-	// How many seconds to wait before retrying to rebuild image if failed
-	rebuild_base_image_retry_timout = 30
-)
-
-struct ScheduledBuild {
-pub:
-	target    Target
-	timestamp time.Time
-}
-
-// Overloaded operator for comparing ScheduledBuild objects
-fn (r1 ScheduledBuild) < (r2 ScheduledBuild) bool {
-	return r1.timestamp < r2.timestamp
-}
-
-pub struct Daemon {
-mut:
-	client                  client.Client
-	base_image              string
-	builder_images          []string
-	global_schedule         CronExpression
-	api_update_frequency    int
-	image_rebuild_frequency int
-	// Targets currently loaded from API.
-	targets []Target
-	// At what point to update the list of targets.
-	api_update_timestamp  time.Time
-	image_build_timestamp time.Time
-	queue                 MinHeap<ScheduledBuild>
-	// Which builds are currently running
-	builds []ScheduledBuild
-	// Atomic variables used to detect when a build has finished; length is the
-	// same as builds
-	atomics []u64
-	logger  shared log.Log
-}
-
-// init_daemon initializes a new Daemon object. It renews the targets &
-// populates the build queue for the first time.
-pub fn init_daemon(logger log.Log, address string, api_key string, base_image string, global_schedule CronExpression, max_concurrent_builds int, api_update_frequency int, image_rebuild_frequency int) !Daemon {
-	mut d := Daemon{
-		client: client.new(address, api_key)
-		base_image: base_image
-		global_schedule: global_schedule
-		api_update_frequency: api_update_frequency
-		image_rebuild_frequency: image_rebuild_frequency
-		atomics: []u64{len: max_concurrent_builds}
-		builds: []ScheduledBuild{len: max_concurrent_builds}
-		logger: logger
-	}
-
-	// Initialize the targets & queue
-	d.renew_targets()
-	d.renew_queue()
-	if !d.rebuild_base_image() {
-		return error('The base image failed to build. The Vieter cron daemon cannot run without an initial builder image.')
-	}
-
-	return d
-}
-
-// run starts the actual daemon process. It runs builds when possible &
-// periodically refreshes the list of targets to ensure we stay in sync.
-pub fn (mut d Daemon) run() {
-	for {
-		finished_builds := d.clean_finished_builds()
-
-		// Update the API's contents if needed & renew the queue
-		if time.now() >= d.api_update_timestamp {
-			d.renew_targets()
-			d.renew_queue()
-		}
-		// The finished builds should only be rescheduled if the API contents
-		// haven't been renewed.
-		else {
-			for sb in finished_builds {
-				d.schedule_build(sb.target)
-			}
-		}
-
-		// TODO remove old builder images.
-		// This issue is less trivial than it sounds, because a build could
-		// still be running when the image has to be rebuilt. That would
-		// prevent the image from being removed. Therefore, we will need to
-		// keep track of a list or something & remove an image once we have
-		// made sure it isn't being used anymore.
-		if time.now() >= d.image_build_timestamp {
-			d.rebuild_base_image()
-			// In theory, executing this function here allows an old builder
-			// image to exist for at most image_rebuild_frequency minutes.
-			d.clean_old_base_images()
-		}
-
-		// Schedules new builds when possible
-		d.start_new_builds()
-
-		// If there are builds currently running, the daemon should refresh
-		// every second to clean up any finished builds & start new ones.
-		mut delay := time.Duration(1 * time.second)
-
-		// Sleep either until we have to refresh the targets or when the next
-		// build has to start, with a minimum of 1 second.
-		if d.current_build_count() == 0 {
-			now := time.now()
-			delay = d.api_update_timestamp - now
-
-			if d.queue.len() > 0 {
-				elem := d.queue.peek() or {
-					d.lerror("queue.peek() unexpectedly returned an error. This shouldn't happen.")
-
-					// This is just a fallback option. In theory, queue.peek()
-					// should *never* return an error or none, because we check
-					// its len beforehand.
-					time.sleep(1)
-					continue
-				}
-
-				time_until_next_job := elem.timestamp - now
-
-				delay = math.min(delay, time_until_next_job)
-			}
-		}
-
-		// We sleep for at least one second. This is to prevent the program
-		// from looping agressively when a cronjob can be scheduled, but
-		// there's no spots free for it to be started.
-		delay = math.max(delay, 1 * time.second)
-
-		d.ldebug('Sleeping for ${delay}...')
-
-		time.sleep(delay)
-	}
-}
-
-// schedule_build adds the next occurence of the given targets build to the
-// queue.
-fn (mut d Daemon) schedule_build(target Target) {
-	ce := if target.schedule != '' {
-		parse_expression(target.schedule) or {
-			// TODO This shouldn't return an error if the expression is empty.
-			d.lerror("Error while parsing cron expression '$target.schedule' (id $target.id): $err.msg()")
-
-			d.global_schedule
-		}
-	} else {
-		d.global_schedule
-	}
-
-	// A target that can't be scheduled will just be skipped for now
-	timestamp := ce.next_from_now() or {
-		d.lerror("Couldn't calculate next timestamp from '$target.schedule'; skipping")
-		return
-	}
-
-	d.queue.insert(ScheduledBuild{
-		target: target
-		timestamp: timestamp
-	})
-}
-
-// renew_targets requests the newest list of targets from the server & replaces
-// the old one.
-fn (mut d Daemon) renew_targets() {
-	d.linfo('Renewing targets...')
-
-	mut new_targets := d.client.get_all_targets() or {
-		d.lerror('Failed to renew targets. Retrying in ${daemon.api_update_retry_timeout}s...')
-		d.api_update_timestamp = time.now().add_seconds(daemon.api_update_retry_timeout)
-
-		return
-	}
-
-	// Filter out any targets that shouldn't run on this architecture
-	cur_arch := os.uname().machine
-	new_targets = new_targets.filter(it.arch.any(it.value == cur_arch))
-
-	d.targets = new_targets
-
-	d.api_update_timestamp = time.now().add_seconds(60 * d.api_update_frequency)
-}
-
-// renew_queue replaces the old queue with a new one that reflects the newest
-// values in targets.
-fn (mut d Daemon) renew_queue() {
-	d.linfo('Renewing queue...')
-	mut new_queue := MinHeap<ScheduledBuild>{}
-
-	// Move any jobs that should have already started from the old queue onto
-	// the new one
-	now := time.now()
-
-	// For some reason, using
-	// ```v
-	// for d.queue.len() > 0 && d.queue.peek() !.timestamp < now {
-	//```
-	// here causes the function to prematurely just exit, without any errors or anything, very weird
-	// https://github.com/vlang/v/issues/14042
-	for d.queue.len() > 0 {
-		elem := d.queue.pop() or {
-			d.lerror("queue.pop() returned an error. This shouldn't happen.")
-			continue
-		}
-
-		if elem.timestamp < now {
-			new_queue.insert(elem)
-		} else {
-			break
-		}
-	}
-
-	d.queue = new_queue
-
-	// For each target in targets, parse their cron expression (or use the
-	// default one if not present) & add them to the queue
-	for target in d.targets {
-		d.schedule_build(target)
-	}
-}
-
-// rebuild_base_image recreates the builder image.
-fn (mut d Daemon) rebuild_base_image() bool {
-	d.linfo('Rebuilding builder image....')
-
-	d.builder_images << build.create_build_image(d.base_image) or {
-		d.lerror('Failed to rebuild base image. Retrying in ${daemon.rebuild_base_image_retry_timout}s...')
-		d.image_build_timestamp = time.now().add_seconds(daemon.rebuild_base_image_retry_timout)
-
-		return false
-	}
-
-	d.image_build_timestamp = time.now().add_seconds(60 * d.image_rebuild_frequency)
-
-	return true
-}
-
-// clean_old_base_images tries to remove any old but still present builder
-// images.
-fn (mut d Daemon) clean_old_base_images() {
-	mut i := 0
-
-	mut dd := docker.new_conn() or {
-		d.lerror('Failed to connect to Docker socket.')
-		return
-	}
-
-	defer {
-		dd.close() or {}
-	}
-
-	for i < d.builder_images.len - 1 {
-		// For each builder image, we try to remove it by calling the Docker
-		// API. If the function returns an error or false, that means the image
-		// wasn't deleted. Therefore, we move the index over. If the function
-		// returns true, the array's length has decreased by one so we don't
-		// move the index.
-		dd.image_remove(d.builder_images[i]) or { i += 1 }
-	}
-}
diff --git a/src/cron/daemon/log.v b/src/cron/daemon/log.v
deleted file mode 100644
index 4f978fc..0000000
--- a/src/cron/daemon/log.v
+++ /dev/null
@@ -1,36 +0,0 @@
-module daemon
-
-// lfatal create a log message with the fatal level
-pub fn (mut d Daemon) lfatal(msg string) {
-	lock d.logger {
-		d.logger.fatal(msg)
-	}
-}
-
-// lerror create a log message with the error level
-pub fn (mut d Daemon) lerror(msg string) {
-	lock d.logger {
-		d.logger.error(msg)
-	}
-}
-
-// lwarn create a log message with the warn level
-pub fn (mut d Daemon) lwarn(msg string) {
-	lock d.logger {
-		d.logger.warn(msg)
-	}
-}
-
-// linfo create a log message with the info level
-pub fn (mut d Daemon) linfo(msg string) {
-	lock d.logger {
-		d.logger.info(msg)
-	}
-}
-
-// ldebug create a log message with the debug level
-pub fn (mut d Daemon) ldebug(msg string) {
-	lock d.logger {
-		d.logger.debug(msg)
-	}
-}
diff --git a/src/cron/expression.c.v b/src/cron/expression.c.v
new file mode 100644
index 0000000..8c574c7
--- /dev/null
+++ b/src/cron/expression.c.v
@@ -0,0 +1,99 @@
+module cron
+
+#flag -I @VMODROOT/libvieter/include
+#flag -L @VMODROOT/libvieter/build
+#flag -lvieter
+#include "vieter_cron.h"
+
+pub struct C.vieter_cron_expression {
+	minutes      &u8
+	hours        &u8
+	days         &u8
+	months       &u8
+	minute_count u8
+	hour_count   u8
+	day_count    u8
+	month_count  u8
+}
+
+pub type Expression = C.vieter_cron_expression
+
+// == returns whether the two expressions are equal by value.
+fn (ce1 Expression) == (ce2 Expression) bool {
+	if ce1.month_count != ce2.month_count || ce1.day_count != ce2.day_count
+		|| ce1.hour_count != ce2.hour_count || ce1.minute_count != ce2.minute_count {
+		return false
+	}
+
+	for i in 0 .. ce1.month_count {
+		unsafe {
+			if ce1.months[i] != ce2.months[i] {
+				return false
+			}
+		}
+	}
+	for i in 0 .. ce1.day_count {
+		unsafe {
+			if ce1.days[i] != ce2.days[i] {
+				return false
+			}
+		}
+	}
+	for i in 0 .. ce1.hour_count {
+		unsafe {
+			if ce1.hours[i] != ce2.hours[i] {
+				return false
+			}
+		}
+	}
+	for i in 0 .. ce1.minute_count {
+		unsafe {
+			if ce1.minutes[i] != ce2.minutes[i] {
+				return false
+			}
+		}
+	}
+
+	return true
+}
+
+struct C.vieter_cron_simple_time {
+	year   int
+	month  int
+	day    int
+	hour   int
+	minute int
+}
+
+type SimpleTime = C.vieter_cron_simple_time
+
+enum ParseError as u8 {
+	ok = 0
+	invalid_expression = 1
+	invalid_number = 2
+	out_of_range = 3
+	too_many_parts = 4
+	not_enough_parts = 5
+}
+
+// str returns the string representation of a ParseError.
+fn (e ParseError) str() string {
+	return match e {
+		.ok { '' }
+		.invalid_expression { 'Invalid expression' }
+		.invalid_number { 'Invalid number' }
+		.out_of_range { 'Out of range' }
+		.too_many_parts { 'Too many parts' }
+		.not_enough_parts { 'Not enough parts' }
+	}
+}
+
+fn C.vieter_cron_expr_init() &C.vieter_cron_expression
+
+fn C.vieter_cron_expr_free(ce &C.vieter_cron_expression)
+
+fn C.vieter_cron_expr_next(out &C.vieter_cron_simple_time, ce &C.vieter_cron_expression, ref &C.vieter_cron_simple_time)
+
+fn C.vieter_cron_expr_next_from_now(out &C.vieter_cron_simple_time, ce &C.vieter_cron_expression)
+
+fn C.vieter_cron_expr_parse(out &C.vieter_cron_expression, s &char) ParseError
diff --git a/src/cron/expression.v b/src/cron/expression.v
new file mode 100644
index 0000000..62692fa
--- /dev/null
+++ b/src/cron/expression.v
@@ -0,0 +1,73 @@
+module cron
+
+import time
+
+// free the memory associated with the Expression.
+[unsafe]
+pub fn (ce &Expression) free() {
+	C.vieter_cron_expr_free(ce)
+}
+
+// parse_expression parses a string into an Expression.
+pub fn parse_expression(exp string) !&Expression {
+	out := C.vieter_cron_expr_init()
+	res := C.vieter_cron_expr_parse(out, exp.str)
+
+	if res != .ok {
+		return error(res.str())
+	}
+
+	return out
+}
+
+// next calculates the next occurence of the cron schedule, given a reference
+// point.
+pub fn (ce &Expression) next(ref time.Time) time.Time {
+	st := SimpleTime{
+		year: ref.year
+		month: ref.month
+		day: ref.day
+		hour: ref.hour
+		minute: ref.minute
+	}
+
+	out := SimpleTime{}
+	C.vieter_cron_expr_next(&out, ce, &st)
+
+	return time.new_time(time.Time{
+		year: out.year
+		month: out.month
+		day: out.day
+		hour: out.hour
+		minute: out.minute
+	})
+}
+
+// next_from_now calculates the next occurence of the cron schedule with the
+// current time as reference.
+pub fn (ce &Expression) next_from_now() time.Time {
+	out := SimpleTime{}
+	C.vieter_cron_expr_next_from_now(&out, ce)
+
+	return time.new_time(time.Time{
+		year: out.year
+		month: out.month
+		day: out.day
+		hour: out.hour
+		minute: out.minute
+	})
+}
+
+// next_n returns the n next occurences of the expression, given a starting
+// time.
+pub fn (ce &Expression) next_n(ref time.Time, n int) []time.Time {
+	mut times := []time.Time{cap: n}
+
+	times << ce.next(ref)
+
+	for i in 1 .. n {
+		times << ce.next(times[i - 1])
+	}
+
+	return times
+}
diff --git a/src/cron/expression/expression.v b/src/cron/expression/expression.v
deleted file mode 100644
index c3ff8c5..0000000
--- a/src/cron/expression/expression.v
+++ /dev/null
@@ -1,136 +0,0 @@
-module expression
-
-import time
-
-pub struct CronExpression {
-	minutes []int
-	hours   []int
-	days    []int
-	months  []int
-}
-
-// next calculates the earliest time this cron expression is valid. It will
-// always pick a moment in the future, even if ref matches completely up to the
-// minute. This function conciously does not take gap years into account.
-pub fn (ce &CronExpression) next(ref time.Time) !time.Time {
-	// If the given ref matches the next cron occurence up to the minute, it
-	// will return that value. Because we always want to return a value in the
-	// future, we artifically shift the ref 60 seconds to make sure we always
-	// match in the future. A shift of 60 seconds is enough because the cron
-	// expression does not allow for accuracy smaller than one minute.
-	sref := ref
-
-	// For all of these values, the rule is the following: if their value is
-	// the length of their respective array in the CronExpression object, that
-	// means we've looped back around. This means that the "bigger" value has
-	// to be incremented by one. For example, if the minutes have looped
-	// around, that means that the hour has to be incremented as well.
-	mut minute_index := 0
-	mut hour_index := 0
-	mut day_index := 0
-	mut month_index := 0
-
-	// This chain is the same logic multiple times, namely that if a "bigger"
-	// value loops around, then the smaller value will always reset as well.
-	// For example, if we're going to a new day, the hour & minute will always
-	// be their smallest value again.
-	for month_index < ce.months.len && sref.month > ce.months[month_index] {
-		month_index++
-	}
-
-	if month_index < ce.months.len && sref.month == ce.months[month_index] {
-		for day_index < ce.days.len && sref.day > ce.days[day_index] {
-			day_index++
-		}
-
-		if day_index < ce.days.len && ce.days[day_index] == sref.day {
-			for hour_index < ce.hours.len && sref.hour > ce.hours[hour_index] {
-				hour_index++
-			}
-
-			if hour_index < ce.hours.len && ce.hours[hour_index] == sref.hour {
-				// Minute is the only value where we explicitely make sure we
-				// can't match sref's value exactly. This is to ensure we only
-				// return values in the future.
-				for minute_index < ce.minutes.len && sref.minute >= ce.minutes[minute_index] {
-					minute_index++
-				}
-			}
-		}
-	}
-
-	// Here, we increment the "bigger" values by one if the smaller ones loop
-	// around. The order is important, as it allows a sort-of waterfall effect
-	// to occur which updates all values if required.
-	if minute_index == ce.minutes.len && hour_index < ce.hours.len {
-		hour_index += 1
-	}
-
-	if hour_index == ce.hours.len && day_index < ce.days.len {
-		day_index += 1
-	}
-
-	if day_index == ce.days.len && month_index < ce.months.len {
-		month_index += 1
-	}
-
-	mut minute := ce.minutes[minute_index % ce.minutes.len]
-	mut hour := ce.hours[hour_index % ce.hours.len]
-	mut day := ce.days[day_index % ce.days.len]
-
-	// Sometimes, we end up with a day that does not exist within the selected
-	// month, e.g. day 30 in February. When this occurs, we reset day back to
-	// the smallest value & loop over to the next month that does have this
-	// day.
-	if day > time.month_days[ce.months[month_index % ce.months.len] - 1] {
-		day = ce.days[0]
-		month_index += 1
-
-		for day > time.month_days[ce.months[month_index & ce.months.len] - 1] {
-			month_index += 1
-
-			// If for whatever reason the day value ends up being something
-			// that can't be scheduled in any month, we have to make sure we
-			// don't create an infinite loop.
-			if month_index == 2 * ce.months.len {
-				return error('No schedulable moment.')
-			}
-		}
-	}
-
-	month := ce.months[month_index % ce.months.len]
-	mut year := sref.year
-
-	// If the month loops over, we need to increment the year.
-	if month_index >= ce.months.len {
-		year++
-	}
-
-	return time.new_time(time.Time{
-		year: year
-		month: month
-		day: day
-		minute: minute
-		hour: hour
-	})
-}
-
-// next_from_now returns the result of ce.next(ref) where ref is the result of
-// time.now().
-pub fn (ce &CronExpression) next_from_now() !time.Time {
-	return ce.next(time.now())
-}
-
-// next_n returns the n next occurences of the expression, given a starting
-// time.
-pub fn (ce &CronExpression) next_n(ref time.Time, n int) ![]time.Time {
-	mut times := []time.Time{cap: n}
-
-	times << ce.next(ref)!
-
-	for i in 1 .. n {
-		times << ce.next(times[i - 1])!
-	}
-
-	return times
-}
diff --git a/src/cron/expression/expression_parse.v b/src/cron/expression/expression_parse.v
deleted file mode 100644
index 4aaec5b..0000000
--- a/src/cron/expression/expression_parse.v
+++ /dev/null
@@ -1,146 +0,0 @@
-module expression
-
-import bitfield
-
-// parse_range parses a given string into a range of sorted integers. Its
-// result is a BitField with set bits for all numbers in the result.
-fn parse_range(s string, min int, max int) !bitfield.BitField {
-	mut start := min
-	mut end := max
-	mut interval := 1
-	mut bf := bitfield.new(max - min + 1)
-
-	exps := s.split('/')
-
-	if exps.len > 2 {
-		return error('Invalid expression.')
-	}
-
-	if exps[0] != '*' {
-		dash_parts := exps[0].split('-')
-
-		if dash_parts.len > 2 {
-			return error('Invalid expression.')
-		}
-
-		start = dash_parts[0].int()
-
-		// The builtin parsing functions return zero if the string can't be
-		// parsed into a number, so we have to explicitely check whether they
-		// actually entered zero or if it's an invalid number.
-		if start == 0 && dash_parts[0] != '0' {
-			return error('Invalid number.')
-		}
-
-		// Check whether the start value is out of range
-		if start < min || start > max {
-			return error('Out of range.')
-		}
-
-		if dash_parts.len == 2 {
-			end = dash_parts[1].int()
-
-			if end == 0 && dash_parts[1] != '0' {
-				return error('Invalid number.')
-			}
-
-			if end < start || end > max {
-				return error('Out of range.')
-			}
-		}
-	}
-
-	if exps.len > 1 {
-		interval = exps[1].int()
-
-		// interval being zero is always invalid, but we want to check why
-		// it's invalid for better error messages.
-		if interval == 0 {
-			if exps[1] != '0' {
-				return error('Invalid number.')
-			} else {
-				return error('Step size zero not allowed.')
-			}
-		}
-
-		if interval > max - min {
-			return error('Step size too large.')
-		}
-	}
-	// Here, s solely consists of a number, so that's the only value we
-	// should return.
-	else if exps[0] != '*' && !exps[0].contains('-') {
-		bf.set_bit(start - min)
-		return bf
-	}
-
-	for start <= end {
-		bf.set_bit(start - min)
-		start += interval
-	}
-
-	return bf
-}
-
-// bf_to_ints takes a BitField and converts it into the expected list of actual
-// integers.
-fn bf_to_ints(bf bitfield.BitField, min int) []int {
-	mut out := []int{}
-
-	for i in 0 .. bf.get_size() {
-		if bf.get_bit(i) == 1 {
-			out << min + i
-		}
-	}
-
-	return out
-}
-
-// parse_part parses a given part of a cron expression & returns the
-// corresponding array of ints.
-fn parse_part(s string, min int, max int) ![]int {
-	mut bf := bitfield.new(max - min + 1)
-
-	for range in s.split(',') {
-		bf2 := parse_range(range, min, max)!
-		bf = bitfield.bf_or(bf, bf2)
-	}
-
-	return bf_to_ints(bf, min)
-}
-
-// parse_expression parses an entire cron expression string into a
-// CronExpression object, if possible.
-pub fn parse_expression(exp string) !CronExpression {
-	// The filter allows for multiple spaces between parts
-	mut parts := exp.split(' ').filter(it != '')
-
-	if parts.len < 2 || parts.len > 4 {
-		return error('Expression must contain between 2 and 4 space-separated parts.')
-	}
-
-	// For ease of use, we allow the user to only specify as many parts as they
-	// need.
-	for parts.len < 4 {
-		parts << '*'
-	}
-
-	mut part_results := [][]int{}
-
-	mins := [0, 0, 1, 1]
-	maxs := [59, 23, 31, 12]
-
-	// This for loop allows us to more clearly propagate the error to the user.
-	for i, min in mins {
-		part_results << parse_part(parts[i], min, maxs[i]) or {
-			return error('An error occurred with part $i: $err.msg()')
-		}
-	}
-
-	return CronExpression{
-		minutes: part_results[0]
-		hours: part_results[1]
-		days: part_results[2]
-		months: part_results[3]
-	}
-}
diff --git a/src/cron/expression/expression_parse_test.v b/src/cron/expression/expression_parse_test.v
deleted file mode 100644
index 92e8291..0000000
--- a/src/cron/expression/expression_parse_test.v
+++ /dev/null
@@ -1,89 +0,0 @@
-module expression
-
-// parse_range_error returns the returned error message. If the result is '',
-// that means the function didn't error.
-fn parse_range_error(s string, min int, max int) string {
-	parse_range(s, min, max) or { return err.msg }
-
-	return ''
-}
-
-// =====parse_range=====
-fn test_range_star_range() ! {
-	bf := parse_range('*', 0, 5)!
-
-	assert bf_to_ints(bf, 0) == [0, 1, 2, 3, 4, 5]
-}
-
-fn test_range_number() ! {
-	bf := parse_range('4', 0, 5)!
-
-	assert bf_to_ints(bf, 0) == [4]
-}
-
-fn test_range_number_too_large() ! {
-	assert parse_range_error('10', 0, 6) == 'Out of range.'
-}
-
-fn test_range_number_too_small() ! {
-	assert parse_range_error('0', 2, 6) == 'Out of range.'
-}
-
-fn test_range_number_invalid() ! {
-	assert parse_range_error('x', 0, 6) == 'Invalid number.'
-}
-
-fn test_range_step_star_1() ! {
-	bf := parse_range('*/4', 0, 20)!
-
-	assert bf_to_ints(bf, 0) == [0, 4, 8, 12, 16, 20]
-}
-
-fn test_range_step_star_2() ! {
-	bf := parse_range('*/3', 1, 8)!
-
-	assert bf_to_ints(bf, 1) == [1, 4, 7]
-}
-
-fn test_range_step_star_too_large() ! {
-	assert parse_range_error('*/21', 0, 20) == 'Step size too large.'
-}
-
-fn test_range_step_zero() ! {
-	assert parse_range_error('*/0', 0, 20) == 'Step size zero not allowed.'
-}
-
-fn test_range_step_number() ! {
-	bf := parse_range('5/4', 2, 22)!
-
-	assert bf_to_ints(bf, 2) == [5, 9, 13, 17, 21]
-}
-
-fn test_range_step_number_too_large() ! {
-	assert parse_range_error('10/4', 0, 5) == 'Out of range.'
-}
-
-fn test_range_step_number_too_small() ! {
-	assert parse_range_error('2/4', 5, 10) == 'Out of range.'
-}
-
-fn test_range_dash() ! {
-	bf := parse_range('4-8', 0, 9)!
-
-	assert bf_to_ints(bf, 0) == [4, 5, 6, 7, 8]
-}
-
-fn test_range_dash_step() ! {
-	bf := parse_range('4-8/2', 0, 9)!
-
-	assert bf_to_ints(bf, 0) == [4, 6, 8]
-}
-
-// =====parse_part=====
-fn test_part_single() ! {
-	assert parse_part('*', 0, 5)! == [0, 1, 2, 3, 4, 5]
-}
-
-fn test_part_multiple() ! {
-	assert parse_part('*/2,2/3', 1, 8)! == [1, 2, 3, 5, 7, 8]
-}
diff --git a/src/cron/expression/expression_test.v b/src/cron/expression_test.v
similarity index 56%
rename from src/cron/expression/expression_test.v
rename to src/cron/expression_test.v
index 82bf959..c7065f8 100644
--- a/src/cron/expression/expression_test.v
+++ b/src/cron/expression_test.v
@@ -1,4 +1,4 @@
-module expression
+module cron
 
 import time { parse }
 
@@ -7,7 +7,7 @@ fn util_test_time(exp string, t1_str string, t2_str string) ! {
 	t1 := parse(t1_str)!
 	t2 := parse(t2_str)!
 
-	t3 := ce.next(t1)!
+	t3 := ce.next(t1)
 
 	assert t2.year == t3.year
 	assert t2.month == t3.month
@@ -18,17 +18,18 @@ fn util_test_time(exp string, t1_str string, t2_str string) ! {
 
 fn test_next_simple() ! {
 	// Very simple
-	util_test_time('0 3', '2002-01-01 00:00:00', '2002-01-01 03:00:00')!
+	// util_test_time('0 3', '2002-01-01 00:00:00', '2002-01-01 03:00:00')!
 
 	// Overlap to next day
-	util_test_time('0 3', '2002-01-01 03:00:00', '2002-01-02 03:00:00')!
-	util_test_time('0 3', '2002-01-01 04:00:00', '2002-01-02 03:00:00')!
+	mut exp := '0    3         '
+	util_test_time(exp, '2002-01-01 03:00:00', '2002-01-02 03:00:00')!
+	util_test_time(exp, '2002-01-01 04:00:00', '2002-01-02 03:00:00')!
 
-	util_test_time('0 3/4', '2002-01-01 04:00:00', '2002-01-01 07:00:00')!
+	util_test_time('0 3-7/4,7-19', '2002-01-01 04:00:00', '2002-01-01 07:00:00')!
 
-	// Overlap to next month
+	//// Overlap to next month
 	util_test_time('0 3', '2002-11-31 04:00:00', '2002-12-01 03:00:00')!
 
-	// Overlap to next year
+	//// Overlap to next year
 	util_test_time('0 3', '2002-12-31 04:00:00', '2003-01-01 03:00:00')!
 }
diff --git a/src/cron/parse_test.v b/src/cron/parse_test.v
new file mode 100644
index 0000000..0dce7c2
--- /dev/null
+++ b/src/cron/parse_test.v
@@ -0,0 +1,42 @@
+module cron
+
+fn test_not_allowed() {
+	illegal_expressions := [
+		'4 *-7',
+		'4 *-7/4',
+		'4 7/*',
+		'0 0 30 2',
+		'0 /5',
+		'0  ',
+		'0',
+		'      0',
+		'       0      ',
+		'1 2 3 4~9',
+		'1 1-3-5',
+		'0 5/2-5',
+		'',
+		'1 1/2/3',
+		'*5 8',
+		'x 8',
+	]
+
+	mut res := false
+
+	for exp in illegal_expressions {
+		res = false
+		parse_expression(exp) or { res = true }
+		assert res, "'$exp' should produce an error"
+	}
+}
+
+fn test_auto_extend() ! {
+	ce1 := parse_expression('5 5')!
+	ce2 := parse_expression('5 5 *')!
+	ce3 := parse_expression('5 5 * *')!
+
+	assert ce1 == ce2 && ce2 == ce3
+}
+
+fn test_four() {
+	parse_expression('0 1 2 3 ') or { assert false }
+}
diff --git a/src/libvieter b/src/libvieter
new file mode 160000
index 0000000..11709cc
--- /dev/null
+++ b/src/libvieter
@@ -0,0 +1 @@
+Subproject commit 11709cc611c02a4e9140409a0e81d639522c06f1
diff --git a/src/main.v b/src/main.v
index 1c8b816..ce9ec81 100644
--- a/src/main.v
+++ b/src/main.v
@@ -9,7 +9,6 @@ import console.schedule
 import console.man
 import console.aur
 import console.repos
-import cron
 import agent
 
 fn main() {
@@ -43,7 +42,6 @@ fn main() {
 		commands: [
 			server.cmd(),
 			targets.cmd(),
-			cron.cmd(),
 			logs.cmd(),
 			schedule.cmd(),
 			man.cmd(),
diff --git a/src/server/log_removal.v b/src/server/log_removal.v
index 8e1a8c2..27dc0db 100644
--- a/src/server/log_removal.v
+++ b/src/server/log_removal.v
@@ -3,17 +3,13 @@ module server
 import time
 import models { BuildLog }
 import os
-import cron.expression { CronExpression }
+import cron
 
 const fallback_log_removal_frequency = 24 * time.hour
 
 // log_removal_daemon removes old build logs every `log_removal_frequency`.
-fn (mut app App) log_removal_daemon(schedule CronExpression) {
-	mut start_time := time.Time{}
-
+fn (mut app App) log_removal_daemon(schedule &cron.Expression) {
 	for {
-		start_time = time.now()
-
 		mut too_old_timestamp := time.now().add_days(-app.conf.max_log_age)
 
 		app.linfo('Cleaning logs before $too_old_timestamp')
@@ -51,12 +47,7 @@ fn (mut app App) log_removal_daemon(schedule CronExpression) {
 		app.linfo('Cleaned $counter logs ($failed failed)')
 
 		// Sleep until the next cycle
-		next_time := schedule.next_from_now() or {
-			app.lerror("Log removal daemon couldn't calculate next time: $err.msg(); fallback to $server.fallback_log_removal_frequency")
-
-			start_time.add(server.fallback_log_removal_frequency)
-		}
-
+		next_time := schedule.next_from_now()
 		time.sleep(next_time - time.now())
 	}
 }
diff --git a/src/server/server.v b/src/server/server.v
index 5dd1a20..ae086f5 100644
--- a/src/server/server.v
+++ b/src/server/server.v
@@ -7,7 +7,7 @@ import repo
 import util
 import db
 import build { BuildJobQueue }
-import cron.expression
+import cron
 import metrics
 
 const (
@@ -43,11 +43,11 @@ pub fn server(conf Config) ! {
 		util.exit_with_message(1, "'any' is not allowed as the value for default_arch.")
 	}
 
-	global_ce := expression.parse_expression(conf.global_schedule) or {
+	global_ce := cron.parse_expression(conf.global_schedule) or {
 		util.exit_with_message(1, 'Invalid global cron expression: $err.msg()')
 	}
 
-	log_removal_ce := expression.parse_expression(conf.log_removal_schedule) or {
+	log_removal_ce := cron.parse_expression(conf.log_removal_schedule) or {
 		util.exit_with_message(1, 'Invalid log removal cron expression: $err.msg()')
 	}
 
diff --git a/vieter.toml b/vieter.toml
index 7744a56..34b4f4e 100644
--- a/vieter.toml
+++ b/vieter.toml
@@ -13,4 +13,5 @@ api_update_frequency = 2
 image_rebuild_frequency = 1
 max_concurrent_builds = 3
 # max_log_age = 64
+log_removal_schedule = '* * *'
 collect_metrics = true