FuchsiaEnv: don't do filesystem locking.
This patch removed the filesystem locking logic from FuchsiaEnv, as
filesystem locking is not available on Fuchsia. We keep the in-process
accounting of locked files which guards against using the same file in
two databases within one process.
Change-Id: I2b946b4e1a47b5db1a86fa2346f99503a6bdb998
diff --git a/util/env_fuchsia.cc b/util/env_fuchsia.cc
index 3ebcaa4..c75b06c 100644
--- a/util/env_fuchsia.cc
+++ b/util/env_fuchsia.cc
@@ -280,27 +280,14 @@
}
};
-static int LockOrUnlock(int fd, bool lock) {
- errno = 0;
- struct flock f;
- memset(&f, 0, sizeof(f));
- f.l_type = (lock ? F_WRLCK : F_UNLCK);
- f.l_whence = SEEK_SET;
- f.l_start = 0;
- f.l_len = 0; // Lock/unlock entire file
- return fcntl(fd, F_SETLK, &f);
-}
-
class FuchsiaFileLock : public FileLock {
public:
- int fd_;
std::string name_;
};
-// Set of locked files. We keep a separate set instead of just
-// relying on fcntrl(F_SETLK) since fcntl(F_SETLK) does not provide
-// any protection against multiple uses from the same process.
-class PosixLockTable {
+// Set of locked files. This is used to guard against multiple uses from one
+// process.
+class LockTable {
private:
port::Mutex mu_;
std::set<std::string> locked_files_;
@@ -453,22 +440,16 @@
return result;
}
+ // Our implementation uses the |locks_| table to guard against creating
+ // multiple databases backed by the same file within one process. This does
+ // not guard against multiple processes using the same file concurrently.
virtual Status LockFile(const std::string& fname, FileLock** lock) {
*lock = NULL;
Status result;
- int fd = open(fname.c_str(), O_RDWR | O_CREAT, 0644);
- if (fd < 0) {
- result = IOError(fname, errno);
- } else if (!locks_.Insert(fname)) {
- close(fd);
+ if (!locks_.Insert(fname)) {
result = Status::IOError("lock " + fname, "already held by process");
- } else if (LockOrUnlock(fd, true) == -1) {
- result = IOError("lock " + fname, errno);
- close(fd);
- locks_.Remove(fname);
} else {
FuchsiaFileLock* my_lock = new FuchsiaFileLock;
- my_lock->fd_ = fd;
my_lock->name_ = fname;
*lock = my_lock;
}
@@ -478,11 +459,7 @@
virtual Status UnlockFile(FileLock* lock) {
FuchsiaFileLock* my_lock = reinterpret_cast<FuchsiaFileLock*>(lock);
Status result;
- if (LockOrUnlock(my_lock->fd_, false) == -1) {
- result = IOError("unlock", errno);
- }
locks_.Remove(my_lock->name_);
- close(my_lock->fd_);
delete my_lock;
return result;
}
@@ -558,7 +535,7 @@
typedef std::deque<BGItem> BGQueue;
BGQueue queue_;
- PosixLockTable locks_;
+ LockTable locks_;
MmapLimiter mmap_limit_;
};
