From b40389bbe2d5eda10e751ea9ab557316ea9738d0 Mon Sep 17 00:00:00 2001
From: Chewing_Bever <roosensjef@gmail.com>
Date: Sun, 12 Nov 2023 12:48:36 +0100
Subject: [PATCH] feat(lsm): implement basic remove

---
 lsm/example/test.c                    | 17 ++++++++++-------
 lsm/include/lsm/store.h               |  7 +++++++
 lsm/src/_include/lsm/store_internal.h |  7 +++++++
 lsm/src/store/lsm_store.c             |  4 ++++
 lsm/src/store/lsm_store_disk_write.c  | 25 +++++++++++++++++++++++++
 lsm/src/store/lsm_store_entry.c       | 13 ++++++++++++-
 6 files changed, 65 insertions(+), 8 deletions(-)

diff --git a/lsm/example/test.c b/lsm/example/test.c
index bd78f2e..660cd04 100644
--- a/lsm/example/test.c
+++ b/lsm/example/test.c
@@ -20,18 +20,13 @@ int main() {
 
   lsm_str *attr;
   lsm_str_init_copy(&attr, "some attribute value");
-  lsm_entry_attr_insert(handle, lsm_attr_type_content_type, attr);
+  lsm_entry_attr_insert(handle, 1, attr);
 
   lsm_str *data;
   lsm_str_init_copy(&data, "hello");
 
   for (int i = 0; i < 50; i++) {
-    lsm_entry_data_append(store, handle, data);
-  }
-
-  if (lsm_entry_sync(store, handle) != lsm_error_ok) {
-    printf("godver");
-    return 1;
+    lsm_entry_data_append(handle, data);
   }
   lsm_entry_close(handle);
 
@@ -50,4 +45,12 @@ int main() {
     total += read;
   }
   printf("\n%lu", total);
+
+  lsm_entry_close(handle);
+
+  assert(lsm_store_open_write(&handle, store, key) == lsm_error_ok);
+  lsm_entry_remove(handle);
+  lsm_entry_close(handle);
+
+  assert(lsm_store_open_read(&handle, store, key) == lsm_error_not_found);
 }
diff --git a/lsm/include/lsm/store.h b/lsm/include/lsm/store.h
index 31eb19b..45eda7e 100644
--- a/lsm/include/lsm/store.h
+++ b/lsm/include/lsm/store.h
@@ -176,6 +176,13 @@ void lsm_entry_close(lsm_entry_handle *handle);
 lsm_error lsm_store_insert(lsm_entry_handle **out, lsm_store *store,
                            lsm_str *key);
 
+/**
+ * Mark the entry as removed.
+ *
+ * @param handle handle to entry to remove
+ */
+void lsm_entry_remove(lsm_entry_handle *handle);
+
 /**
  * Append new data to the given entry, which is expected to be in the store.
  *
diff --git a/lsm/src/_include/lsm/store_internal.h b/lsm/src/_include/lsm/store_internal.h
index fb50838..afbd4f3 100644
--- a/lsm/src/_include/lsm/store_internal.h
+++ b/lsm/src/_include/lsm/store_internal.h
@@ -40,6 +40,13 @@ typedef struct lsm_entry {
  */
 lsm_error lsm_entry_init(lsm_entry **ptr);
 
+/**
+ * Deallocate an existing entry
+ *
+ * @param entry pointer to entry
+ */
+void lsm_entry_free(lsm_entry *entry);
+
 /**
  * Deallocate an existing lsm_entry object.
  *
diff --git a/lsm/src/store/lsm_store.c b/lsm/src/store/lsm_store.c
index 2185418..57eacb7 100644
--- a/lsm/src/store/lsm_store.c
+++ b/lsm/src/store/lsm_store.c
@@ -158,6 +158,10 @@ lsm_error lsm_store_insert(lsm_entry_handle **out, lsm_store *store,
   return lsm_error_ok;
 }
 
+void lsm_entry_remove(lsm_entry_handle *handle) {
+  handle->states |= lsm_entry_handle_state_removed;
+}
+
 lsm_error lsm_entry_data_append(lsm_entry_handle *handle, lsm_str *data) {
   if (lsm_str_len(data) == 0) {
     return lsm_error_ok;
diff --git a/lsm/src/store/lsm_store_disk_write.c b/lsm/src/store/lsm_store_disk_write.c
index acb0015..b5081af 100644
--- a/lsm/src/store/lsm_store_disk_write.c
+++ b/lsm/src/store/lsm_store_disk_write.c
@@ -124,3 +124,28 @@ lsm_error lsm_entry_disk_insert(lsm_entry_handle *handle) {
 
   return res;
 }
+
+// Marking an entry as removed in the idx file is simply setting the length of
+// its entry to zero
+lsm_error lsm_entry_disk_remove(lsm_entry_handle *handle) {
+  lsm_store *store = handle->store;
+  lsm_entry *entry = handle->wrapper->entry;
+
+  pthread_mutex_lock(&store->idx.lock);
+
+  lsm_error res =
+      lsm_fseek(store->idx.f, entry->idx_file_offset + sizeof(uint64_t));
+
+  if (res != lsm_error_ok) {
+    pthread_mutex_unlock(&store->idx.lock);
+
+    return res;
+  }
+
+  uint64_t val = 0;
+  res = lsm_fwrite(NULL, store->idx.f, sizeof(uint64_t), 1, &val);
+
+  pthread_mutex_unlock(&store->idx.lock);
+
+  return res;
+}
diff --git a/lsm/src/store/lsm_store_entry.c b/lsm/src/store/lsm_store_entry.c
index 8212ba6..fd55624 100644
--- a/lsm/src/store/lsm_store_entry.c
+++ b/lsm/src/store/lsm_store_entry.c
@@ -19,6 +19,14 @@ lsm_error lsm_entry_init(lsm_entry **ptr) {
   return lsm_error_ok;
 }
 
+void lsm_entry_free(lsm_entry *entry) {
+  if (entry->attrs.count > 0) {
+    free(entry->attrs.items);
+  }
+
+  free(entry);
+}
+
 lsm_error lsm_entry_wrapper_init(lsm_entry_wrapper **ptr) {
   lsm_entry_wrapper *wrap = calloc(1, sizeof(lsm_entry_wrapper));
 
@@ -58,7 +66,10 @@ void lsm_entry_close(lsm_entry_handle *handle) {
     lsm_entry_disk_insert(handle);
   } else if ((handle->states & lsm_entry_handle_state_removed) &&
              !(handle->states & lsm_entry_handle_state_new)) {
-    /* lsm_entry_disk_remove(handle); */
+    lsm_entry_disk_remove(handle);
+
+    lsm_entry_free(handle->wrapper->entry);
+    handle->wrapper->entry = NULL;
   } else if (handle->states & lsm_entry_handle_state_updated) {
     /* lsm_entry_disk_update(handle); */
   }