feat(lsm): require changes to be committed before writing to persistent

storage

include/lander.h

@@ -51,6 +51,8 @@ lnm_http_step_err lander_post_paste_secure(lnm_http_conn *conn);
 
 lnm_http_step_err lander_stream_body_to_entry(lnm_http_conn *conn);
 
+lnm_http_step_err lander_commit_entry(lnm_http_conn *conn);
+
 lnm_http_step_err lander_post_redirect_body_to_attr(lnm_http_conn *conn);
 
 lnm_http_step_err lander_remove_entry(lnm_http_conn *conn);

lsm/include/lsm/store.h

@@ -159,6 +159,15 @@ lsm_error lsm_store_open_read(lsm_entry_handle **out, lsm_store *store,
 lsm_error lsm_store_open_write(lsm_entry_handle **out, lsm_store *store,
                                const lsm_str *key);
 
+/**
+ * Commit any changes to the persistent storage. Any changes, insertions or
+ * deletions that occured without a commit are reverted when the handle is
+ * closed.
+ *
+ * @param handle handle to the entry
+ */
+lsm_error lsm_entry_commit(lsm_entry_handle *handle);
+
 /**
  * Close an open entry handle.
  *

lsm/src/_include/lsm/store_internal.h

@@ -156,4 +156,12 @@ lsm_error lsm_entry_data_open_read(lsm_entry_handle *handle);
  */
 lsm_error lsm_entry_data_open_write(lsm_entry_handle *handle);
 
+/**
+ * Remove the entry's data file if present and close its handle. Any uncommitted
+ * changes will be reverted.
+ *
+ * @param handle handle to the entry
+ */
+lsm_error lsm_entry_data_remove(lsm_entry_handle *handle);
+
 #endif

lsm/src/store/lsm_store_disk_write.c

@@ -153,20 +153,7 @@ lsm_error lsm_entry_disk_remove(lsm_entry_handle *handle) {
 
   fflush(store->idx.f);
 
-  // Remove data file if present
+  LSM_RES(lsm_entry_data_remove(handle));
-  if (entry->data_len > 0) {
-    if (handle->f != NULL) {
-      fclose(handle->f);
-      handle->f = NULL;
-    }
-
-    char data_path[lsm_entry_data_path_len(handle) + 1];
-    lsm_entry_data_path(data_path, handle);
-
-    if (remove(data_path) != 0) {
-      return lsm_error_failed_io;
-    }
-  }
 
   return lsm_error_ok;
 }

lsm/src/store/lsm_store_entry.c

@@ -58,23 +58,45 @@ lsm_error lsm_entry_handle_init(lsm_entry_handle **out) {
   return lsm_error_ok;
 }
 
-void lsm_entry_close(lsm_entry_handle *handle) {
+lsm_error lsm_entry_commit(lsm_entry_handle *handle) {
-  if (handle->f != NULL) {
+  uint8_t state_new = handle->states & lsm_entry_handle_state_new;
-    fclose(handle->f);
+  uint8_t state_removed = handle->states & lsm_entry_handle_state_removed;
-  }
 
-  // TODO handle errors here
+  // Clean new entry
-  if ((handle->states & lsm_entry_handle_state_new) &&
+  if (state_new && !state_removed) {
-      !(handle->states & lsm_entry_handle_state_removed)) {
+    LSM_RES(lsm_entry_disk_insert(handle));
-    lsm_entry_disk_insert(handle);
+  }
-  } else if ((handle->states & lsm_entry_handle_state_removed) &&
+  // Previously stored entry that needs to be removed; should be removed from db
-             !(handle->states & lsm_entry_handle_state_new)) {
+  // file as well
-    lsm_entry_disk_remove(handle);
+  else if (state_removed && !state_new) {
+    LSM_RES(lsm_entry_disk_remove(handle));
+
+    lsm_entry_free(handle->wrapper->entry);
+    handle->wrapper->entry = NULL;
+  }
+
+  // Reset states after committing current changes
+  handle->states = 0;
+
+  return lsm_error_ok;
+}
+
+void lsm_entry_close(lsm_entry_handle *handle) {
+  if (handle->f != NULL) {
+    fclose(handle->f);
+    handle->f = NULL;
+  }
+
+  uint8_t state_new = handle->states & lsm_entry_handle_state_new;
+  /* bool state_updated = handle->states & lsm_entry_handle_state_updated; */
+
+  // New entries create a wrapper in the trie that should be removed if not
+  // committed
+  if (state_new) {
+    lsm_entry_data_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); */
   }
 
   pthread_rwlock_unlock(&handle->wrapper->lock);
@@ -316,3 +338,23 @@ lsm_error lsm_entry_data_open_read(lsm_entry_handle *handle) {
 
   return lsm_error_ok;
 }
+
+lsm_error lsm_entry_data_remove(lsm_entry_handle *handle) {
+  const lsm_entry *entry = handle->wrapper->entry;
+
+  if (entry->data_len > 0) {
+    if (handle->f != NULL) {
+      fclose(handle->f);
+      handle->f = NULL;
+    }
+
+    char data_path[lsm_entry_data_path_len(handle) + 1];
+    lsm_entry_data_path(data_path, handle);
+
+    if (remove(data_path) != 0) {
+      return lsm_error_failed_io;
+    }
+  }
+
+  return lsm_error_ok;
+}

src/lander/lander_steps.c

@@ -1,6 +1,7 @@
 #include <string.h>
 
 #include "lnm/http/loop.h"
+#include "lnm/log.h"
 #include "lnm/loop.h"
 
 #include "lander.h"
@@ -25,3 +26,12 @@ lnm_http_step_err lander_stream_body_to_entry(lnm_http_conn *conn) {
              ? lnm_http_step_err_done
              : lnm_http_step_err_io_needed;
 }
+
+lnm_http_step_err lander_commit_entry(lnm_http_conn *conn) {
+  lnm_http_loop_ctx *ctx = conn->ctx;
+  lander_ctx *c_ctx = ctx->c;
+
+  lsm_entry_commit(c_ctx->entry);
+
+  return lnm_http_step_err_done;
+}