Rewrite all file IO for more performance

The new `git_filebuf` structure provides atomic high-performance writes
to disk by using a write cache, and optionally a double-buffered scheme
through a worker thread (not enabled yet).

Writes can be done 3-layered, like in git.git (user code -> write cache
-> disk), or 2-layered, by writing directly on the cache. This makes
index writing considerably faster.

The `git_filebuf` structure contains all the old functionality of
`git_filelock` for atomic file writes and reads. The `git_filelock`
structure has been removed.

Additionally, the `git_filebuf` API allows to automatically hash (SHA1)
all the data as it is written to disk (hashing is done smartly on big
chunks to improve performance).

Signed-off-by: Vicent Marti <tanoku@gmail.com>

1 files changed, 0 insertions, 132 deletions

diff --git a/src/filelock.c b/src/filelock.c
deleted file mode 100644
index 9db1cd720..000000000
--- a/src/filelock.c
+++ /dev/null
@@ -1,132 +0,0 @@
-/*
- * This file is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License, version 2,
- * as published by the Free Software Foundation.
- *
- * In addition to the permissions in the GNU General Public License,
- * the authors give you unlimited permission to link the compiled
- * version of this file into combinations with other programs,
- * and to distribute those combinations without any restriction
- * coming from the use of this file.  (The General Public License
- * restrictions do apply in other respects; for example, they cover
- * modification of the file, and distribution when not linked into
- * a combined executable.)
- *
- * This file is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; see the file COPYING.  If not, write to
- * the Free Software Foundation, 51 Franklin Street, Fifth Floor,
- * Boston, MA 02110-1301, USA.
- */
-
-#include "common.h"
-#include "filelock.h"
-#include "fileops.h"
-
-static const char *GIT_FILELOCK_EXTENSION = ".lock\0";
-static const size_t GIT_FILELOCK_EXTLENGTH = 6;
-
-#define BUILD_PATH_LOCK(_lock, _path) { \
-	memcpy(_path, _lock->path, _lock->path_length); \
-	memcpy(_path + _lock->path_length, GIT_FILELOCK_EXTENSION,\
-			GIT_FILELOCK_EXTLENGTH);\
-}
-
-int git_filelock_init(git_filelock *lock, const char *path)
-{
-	if (lock == NULL || path == NULL)
-		return GIT_ERROR;
-
-	memset(lock, 0x0, sizeof(git_filelock));
-
-	lock->path_length = strlen(path);
-
-	if (lock->path_length + GIT_FILELOCK_EXTLENGTH >= GIT_PATH_MAX)
-		return GIT_ERROR;
-
-	memcpy(lock->path, path, lock->path_length);
-	return GIT_SUCCESS;
-}
-
-int git_filelock_lock(git_filelock *lock, int append)
-{
-	char path_lock[GIT_PATH_MAX];
-	BUILD_PATH_LOCK(lock, path_lock);
-
-	/* If file already exists, we cannot create a lock */
-	if (gitfo_exists(path_lock) == 0)
-		return GIT_EOSERR;
-
-	lock->file_lock = gitfo_creat(path_lock, 0666);
-
-	if (lock->file_lock < 0)
-		return GIT_EOSERR;
-
-	lock->is_locked = 1;
-
-	/* TODO: do a flock() in the descriptor file_lock */
-
-	if (append && gitfo_exists(lock->path) == 0) {
-		git_file source;
-		char buffer[2048];
-		size_t read_bytes;
-
-		source = gitfo_open(lock->path, O_RDONLY);
-		if (source < 0)
-			return GIT_EOSERR;
-
-		while ((read_bytes = gitfo_read(source, buffer, 2048)) > 0)
-			gitfo_write(lock->file_lock, buffer, read_bytes);
-
-		gitfo_close(source);
-	}
-
-	return GIT_SUCCESS;
-}
-
-void git_filelock_unlock(git_filelock *lock)
-{
-	char path_lock[GIT_PATH_MAX];
-	BUILD_PATH_LOCK(lock, path_lock);
-
-	if (lock->is_locked) {
-		/* The flock() in lock->file_lock is removed
-		 * automatically when closing the descriptor */
-		gitfo_close(lock->file_lock);
-		gitfo_unlink(path_lock);
-		lock->is_locked = 0;
-	}
-}
-
-int git_filelock_commit(git_filelock *lock)
-{
-	int error;
-	char path_lock[GIT_PATH_MAX];
-	BUILD_PATH_LOCK(lock, path_lock);
-
-	if (!lock->is_locked || lock->file_lock < 0)
-		return GIT_ERROR;
-
-	/* FIXME: flush the descriptor? */
-	gitfo_close(lock->file_lock);
-
-	error = gitfo_move_file(path_lock, lock->path);
-
-	if (error < GIT_SUCCESS)
-		gitfo_unlink(path_lock);
-
-	lock->is_locked = 0;
-	return error;
-}
-
-int git_filelock_write(git_filelock *lock, const void *buffer, size_t length)
-{
-	if (!lock->is_locked || lock->file_lock < 0)
-		return GIT_ERROR;
-
-	return gitfo_write(lock->file_lock, (void *)buffer, length);
-}