Speed up reading of content file disabling mutexes

TODO

@@ -5,6 +5,8 @@ This is the list of TODO items for SnapRAID.
 
 - Next
 
+* Use a memory mapped file to read the content file
+
 * Integration with MergeFS ?
 
 * Evaluate use of syscall getdents64() instead of readdir(): https://linux.die.net/man/2/getdents64

cmdline/elem.c

@@ -765,6 +765,7 @@ struct snapraid_disk* disk_alloc(const char* name, const char* dir, uint64_t dev
 	pathslash(disk->dir, sizeof(disk->dir));
 
 #if HAVE_THREAD
+	disk->single_thread = 0;
 	thread_mutex_init(&disk->fs_mutex);
 #endif
 
@@ -856,7 +857,8 @@ void extra_free(struct snapraid_extra* extra)
 static inline void fs_lock(struct snapraid_disk* disk)
 {
 #if HAVE_THREAD
-	thread_mutex_lock(&disk->fs_mutex);
+	if (!disk->single_thread)
+		thread_mutex_lock(&disk->fs_mutex);
 #else
 	(void)disk;
 #endif
@@ -865,7 +867,8 @@ static inline void fs_lock(struct snapraid_disk* disk)
 static inline void fs_unlock(struct snapraid_disk* disk)
 {
 #if HAVE_THREAD
-	thread_mutex_unlock(&disk->fs_mutex);
+	if (!disk->single_thread)
+		thread_mutex_unlock(&disk->fs_mutex);
 #else
 	(void)disk;
 #endif

cmdline/elem.h

@@ -388,6 +388,8 @@ struct snapraid_disk {
 	int skip_access; /**< If the disk is inaccessible and it should be skipped. */
 
 #if HAVE_THREAD
+	int single_thread; /**< Running in single thread, and then not needing the mutex */
+
 	/**
 	 * Mutex for protecting the filesystem structure.
 	 *

cmdline/state.c

@@ -2133,6 +2133,12 @@ static void state_read_content(struct snapraid_state* state, const char* path, S
 	tommy_array_init(&disk_mapping);
 	tommy_hashdyn_init(&bucket_hash);
 
+	/* mark all disks as single threads */
+	for (tommy_node* i = state->disklist; i != 0; i = i->next) {
+		struct snapraid_disk* disk = i->data;
+		disk->single_thread = 1;
+	}
+
 	ret = sread(f, buffer, 12);
 	if (ret < 0) {
 		/* LCOV_EXCL_START */
@@ -3231,6 +3237,12 @@ static void state_read_content(struct snapraid_state* state, const char* path, S
 		}
 	}
 
+	/* mark all disks as multi threads */
+	for (tommy_node* i = state->disklist; i != 0; i = i->next) {
+		struct snapraid_disk* disk = i->data;
+		disk->single_thread = 0;
+	}
+
 	tommy_array_done(&disk_mapping);
 
 	if (serror(f)) {