vfs/fsm: Add disk methods

Signed-off-by: Mathieu Borderé <[email protected]>

Makefile.am

@@ -21,6 +21,7 @@ libdqlite_la_SOURCES = \
   src/leader.c \
   src/lib/addr.c \
   src/lib/buffer.c \
+  src/lib/fs.c \
   src/lib/transport.c \
   src/logger.c \
   src/message.c \

include/dqlite.h

@@ -197,6 +197,16 @@ int dqlite_node_set_failure_domain(dqlite_node *n, unsigned long long code);
 int dqlite_node_set_snapshot_params(dqlite_node *n, unsigned snapshot_threshold,
                                     unsigned snapshot_trailing);
 
+/**
+ * WARNING: This is an experimental API.
+ *
+ * By default dqlite holds the SQLite database file and WAL in memory. By enabling
+ * disk-mode, dqlite will hold the SQLite database file on-disk while keeping the WAL
+ * in memory. Has to be called after `dqlite_node_create` and before
+ * `dqlite_node_start`.
+ */
+int dqlite_node_enable_disk_mode(dqlite_node *n);
+
 /**
  * Start a dqlite node.
  *
@@ -305,6 +315,8 @@ dqlite_node_id dqlite_generate_node_id(const char *address);
  */
 int dqlite_vfs_init(sqlite3_vfs *vfs, const char *name);
 
+int dqlite_vfs_enable_disk(sqlite3_vfs *vfs);
+
 /**
  * Release all memory used internally by a SQLite VFS object that was
  * initialized using @qlite_vfs_init.
@@ -386,6 +398,11 @@ int dqlite_vfs_shallow_snapshot(sqlite3_vfs *vfs,
 				struct dqlite_buffer bufs[],
 				unsigned n);
 
+int dqlite_vfs_snapshot_disk(sqlite3_vfs *vfs,
+				const char *filename,
+				struct dqlite_buffer bufs[],
+				unsigned n);
+
 /**
  * Return the number of database pages (excluding WAL).
  */
@@ -401,4 +418,12 @@ int dqlite_vfs_restore(sqlite3_vfs *vfs,
 		       const void *data,
 		       size_t n);
 
+/**
+ * Restore a snapshot of the main database file and of the WAL file.
+ */
+int dqlite_vfs_restore_disk(sqlite3_vfs *vfs,
+		       const char *filename,
+		       const void *data,
+		       size_t main_size,
+		       size_t wal_size);
 #endif /* DQLITE_H */

src/config.h

@@ -17,7 +17,7 @@ struct config
 	char name[256];                /* VFS/replication registriatio name */
 	unsigned long long failure_domain; /* User-provided failure domain */
 	unsigned long long int weight;     /* User-provided node weight */
-	char dir[1024];                /* Data dir */
+	char dir[1024];                /* Data dir for on-disk database */
 	bool disk;                     /* Disk-mode or not */
 };
 

src/dqlite.c

@@ -12,6 +12,11 @@ int dqlite_vfs_init(sqlite3_vfs *vfs, const char *name)
 	return VfsInit(vfs, name);
 }
 
+int dqlite_vfs_enable_disk(sqlite3_vfs *vfs)
+{
+	return VfsEnableDisk(vfs);
+}
+
 void dqlite_vfs_close(sqlite3_vfs *vfs)
 {
 	VfsClose(vfs);
@@ -47,6 +52,25 @@ int dqlite_vfs_snapshot(sqlite3_vfs *vfs,
 	return VfsSnapshot(vfs, filename, data, n);
 }
 
+int dqlite_vfs_snapshot_disk(sqlite3_vfs *vfs,
+			const char *filename,
+			struct dqlite_buffer bufs[],
+			unsigned n)
+{
+	int rv;
+	if (n != 2) {
+		return -1;
+	}
+
+	rv = VfsDiskSnapshotDb(vfs, filename, &bufs[0]);
+	if (rv != 0) {
+		return rv;
+	}
+
+	rv = VfsDiskSnapshotWal(vfs, filename, &bufs[1]);
+	return rv;
+}
+
 int dqlite_vfs_num_pages(sqlite3_vfs *vfs,
 			 const char *filename,
 			 unsigned *n)
@@ -69,3 +93,12 @@ int dqlite_vfs_restore(sqlite3_vfs *vfs,
 {
 	return VfsRestore(vfs, filename, data, n);
 }
+
+int dqlite_vfs_restore_disk(sqlite3_vfs *vfs,
+		       const char *filename,
+		       const void *data,
+		       size_t main_size,
+		       size_t wal_size)
+{
+	return VfsDiskRestore(vfs, filename, data, main_size, wal_size);
+}