bool
LFLock_Maybe_Delete_File_IMP(LockFileLock *self, String *path,
bool delete_mine, bool delete_other) {
LockFileLockIVARS *const ivars = LFLock_IVARS(self);
Folder *folder = ivars->folder;
bool success = false;
// Only delete locks that start with our lock name.
if (!Str_Starts_With_Utf8(path, "locks", 5)) {
return false;
}
StringIterator *iter = Str_Top(path);
StrIter_Advance(iter, 5 + 1);
if (!StrIter_Starts_With(iter, ivars->name)) {
DECREF(iter);
return false;
}
DECREF(iter);
// Attempt to delete dead lock file.
if (Folder_Exists(folder, path)) {
Hash *hash = (Hash*)Json_slurp_json(folder, path);
if (hash != NULL && Obj_Is_A((Obj*)hash, HASH)) {
String *pid_buf = (String*)Hash_Fetch_Utf8(hash, "pid", 3);
String *host = (String*)Hash_Fetch_Utf8(hash, "host", 4);
String *name = (String*)Hash_Fetch_Utf8(hash, "name", 4);
// Match hostname and lock name.
if (host != NULL
&& Str_Is_A(host, STRING)
&& Str_Equals(host, (Obj*)ivars->host)
&& name != NULL
&& Str_Is_A(name, STRING)
&& Str_Equals(name, (Obj*)ivars->name)
&& pid_buf != NULL
&& Str_Is_A(pid_buf, STRING)
) {
// Verify that pid is either mine or dead.
int pid = (int)Str_To_I64(pid_buf);
if ((delete_mine && pid == PID_getpid()) // This process.
|| (delete_other && !PID_active(pid)) // Dead pid.
) {
if (Folder_Delete(folder, path)) {
success = true;
}
else {
String *mess
= MAKE_MESS("Can't delete '%o'", path);
DECREF(hash);
Err_throw_mess(ERR, mess);
}
}
}
}
DECREF(hash);
}
return success;
}
LockFileLock*
LFLock_init(LockFileLock *self, Folder *folder, const CharBuf *name,
const CharBuf *host, int32_t timeout, int32_t interval) {
int pid = PID_getpid();
Lock_init((Lock*)self, folder, name, host, timeout, interval);
self->link_path = CB_newf("%o.%o.%i64", self->lock_path, host, pid);
return self;
}
LockFileLock*
LFLock_init(LockFileLock *self, Folder *folder, String *name,
String *host, int32_t timeout, int32_t interval) {
int pid = PID_getpid();
Lock_init((Lock*)self, folder, name, host, timeout, interval);
LockFileLockIVARS *const ivars = LFLock_IVARS(self);
ivars->link_path = Str_newf("%o.%o.%i64", ivars->lock_path, host, pid);
return self;
}
bool_t
LFLock_maybe_delete_file(LockFileLock *self, const CharBuf *path,
bool_t delete_mine, bool_t delete_other) {
Folder *folder = self->folder;
bool_t success = false;
ZombieCharBuf *scratch = ZCB_WRAP(path);
// Only delete locks that start with our lock name.
CharBuf *lock_dir_name = (CharBuf*)ZCB_WRAP_STR("locks", 5);
if (!ZCB_Starts_With(scratch, lock_dir_name)) {
return false;
}
ZCB_Nip(scratch, CB_Get_Size(lock_dir_name) + 1);
if (!ZCB_Starts_With(scratch, self->name)) {
return false;
}
// Attempt to delete dead lock file.
if (Folder_Exists(folder, path)) {
Hash *hash = (Hash*)Json_slurp_json(folder, path);
if (hash != NULL && Obj_Is_A((Obj*)hash, HASH)) {
CharBuf *pid_buf = (CharBuf*)Hash_Fetch_Str(hash, "pid", 3);
CharBuf *host = (CharBuf*)Hash_Fetch_Str(hash, "host", 4);
CharBuf *name
= (CharBuf*)Hash_Fetch_Str(hash, "name", 4);
// Match hostname and lock name.
if (host != NULL
&& CB_Equals(host, (Obj*)self->host)
&& name != NULL
&& CB_Equals(name, (Obj*)self->name)
&& pid_buf != NULL
) {
// Verify that pid is either mine or dead.
int pid = (int)CB_To_I64(pid_buf);
if ((delete_mine && pid == PID_getpid()) // This process.
|| (delete_other && !PID_active(pid)) // Dead pid.
) {
if (Folder_Delete(folder, path)) {
success = true;
}
else {
CharBuf *mess
= MAKE_MESS("Can't delete '%o'", path);
DECREF(hash);
Err_throw_mess(ERR, mess);
}
}
}
}
DECREF(hash);
}
return success;
}
bool_t
LFLock_request(LockFileLock *self) {
Hash *file_data;
bool_t wrote_json;
bool_t success = false;
bool_t deletion_failed = false;
if (Folder_Exists(self->folder, self->lock_path)) {
Err_set_error((Err*)LockErr_new(CB_newf("Can't obtain lock: '%o' exists",
self->lock_path)));
return false;
}
// Create the "locks" subdirectory if necessary.
CharBuf *lock_dir_name = (CharBuf*)ZCB_WRAP_STR("locks", 5);
if (!Folder_Exists(self->folder, lock_dir_name)) {
if (!Folder_MkDir(self->folder, lock_dir_name)) {
Err *mkdir_err = (Err*)CERTIFY(Err_get_error(), ERR);
LockErr *err = LockErr_new(CB_newf("Can't create 'locks' directory: %o",
Err_Get_Mess(mkdir_err)));
// Maybe our attempt failed because another process succeeded.
if (Folder_Find_Folder(self->folder, lock_dir_name)) {
DECREF(err);
}
else {
// Nope, everything failed, so bail out.
Err_set_error((Err*)err);
return false;
}
}
}
// Prepare to write pid, lock name, and host to the lock file as JSON.
file_data = Hash_new(3);
Hash_Store_Str(file_data, "pid", 3,
(Obj*)CB_newf("%i32", (int32_t)PID_getpid()));
Hash_Store_Str(file_data, "host", 4, INCREF(self->host));
Hash_Store_Str(file_data, "name", 4, INCREF(self->name));
// Write to a temporary file, then use the creation of a hard link to
// ensure atomic but non-destructive creation of the lockfile with its
// complete contents.
wrote_json = Json_spew_json((Obj*)file_data, self->folder, self->link_path);
if (wrote_json) {
success = Folder_Hard_Link(self->folder, self->link_path,
self->lock_path);
if (!success) {
Err *hard_link_err = (Err*)CERTIFY(Err_get_error(), ERR);
Err_set_error((Err*)LockErr_new(CB_newf("Failed to obtain lock at '%o': %o",
self->lock_path,
Err_Get_Mess(hard_link_err))));
}
deletion_failed = !Folder_Delete(self->folder, self->link_path);
}
else {
Err *spew_json_err = (Err*)CERTIFY(Err_get_error(), ERR);
Err_set_error((Err*)LockErr_new(CB_newf("Failed to obtain lock at '%o': %o",
self->lock_path,
Err_Get_Mess(spew_json_err))));
}
DECREF(file_data);
// Verify that our temporary file got zapped.
if (wrote_json && deletion_failed) {
CharBuf *mess = MAKE_MESS("Failed to delete '%o'", self->link_path);
Err_throw_mess(ERR, mess);
}
return success;
}
bool
LFLock_Request_IMP(LockFileLock *self) {
LockFileLockIVARS *const ivars = LFLock_IVARS(self);
bool success = false;
if (Folder_Exists(ivars->folder, ivars->lock_path)) {
Err_set_error((Err*)LockErr_new(Str_newf("Can't obtain lock: '%o' exists",
ivars->lock_path)));
return false;
}
// Create the "locks" subdirectory if necessary.
String *lock_dir_name = (String*)SSTR_WRAP_UTF8("locks", 5);
if (!Folder_Exists(ivars->folder, lock_dir_name)) {
if (!Folder_MkDir(ivars->folder, lock_dir_name)) {
Err *mkdir_err = (Err*)CERTIFY(Err_get_error(), ERR);
LockErr *err = LockErr_new(Str_newf("Can't create 'locks' directory: %o",
Err_Get_Mess(mkdir_err)));
// Maybe our attempt failed because another process succeeded.
if (Folder_Find_Folder(ivars->folder, lock_dir_name)) {
DECREF(err);
}
else {
// Nope, everything failed, so bail out.
Err_set_error((Err*)err);
return false;
}
}
}
// Prepare to write pid, lock name, and host to the lock file as JSON.
Hash *file_data = Hash_new(3);
Hash_Store_Utf8(file_data, "pid", 3,
(Obj*)Str_newf("%i32", (int32_t)PID_getpid()));
Hash_Store_Utf8(file_data, "host", 4, INCREF(ivars->host));
Hash_Store_Utf8(file_data, "name", 4, INCREF(ivars->name));
String *json = Json_to_json((Obj*)file_data);
DECREF(file_data);
// Write to a temporary file, then use the creation of a hard link to
// ensure atomic but non-destructive creation of the lockfile with its
// complete contents.
OutStream *outstream = Folder_Open_Out(ivars->folder, ivars->link_path);
if (!outstream) {
ERR_ADD_FRAME(Err_get_error());
DECREF(json);
return false;
}
struct lockfile_context context;
context.outstream = outstream;
context.json = json;
Err *json_error = Err_trap(S_write_lockfile_json, &context);
bool wrote_json = !json_error;
DECREF(outstream);
DECREF(json);
if (wrote_json) {
success = Folder_Hard_Link(ivars->folder, ivars->link_path,
ivars->lock_path);
if (!success) {
Err *hard_link_err = (Err*)CERTIFY(Err_get_error(), ERR);
Err_set_error((Err*)LockErr_new(Str_newf("Failed to obtain lock at '%o': %o",
ivars->lock_path,
Err_Get_Mess(hard_link_err))));
}
}
else {
Err_set_error((Err*)LockErr_new(Str_newf("Failed to obtain lock at '%o': %o",
ivars->lock_path,
Err_Get_Mess(json_error))));
DECREF(json_error);
}
// Verify that our temporary file got zapped.
bool deletion_failed = !Folder_Delete(ivars->folder, ivars->link_path);
if (deletion_failed) {
String *mess = MAKE_MESS("Failed to delete '%o'", ivars->link_path);
Err_throw_mess(ERR, mess);
}
return success;
}