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/* Copyright 2012-present Facebook, Inc.
* Licensed under the Apache License, Version 2.0 */
#include "watchman.h"
#include "watchman_synchronized.h"
using watchman::FileDescriptor;
/** The state saving thread is responsible for writing out the
* persistent information about the users watches.
* It runs in its own thread so that we avoid the possibility
* of self deadlock if various threads were to immediately
* save the state when things are changing.
*
* This uses a simple condition variable to wait for and be
* notified of state changes.
*/
namespace {
struct state {
bool needsSave{false};
};
watchman::Synchronized<state, std::mutex> saveState;
std::condition_variable stateCond;
std::thread state_saver_thread;
}
static bool do_state_save(void);
static void state_saver() {
bool do_save;
w_set_thread_name("statesaver");
while (!w_is_stopping()) {
{
auto state = saveState.wlock();
if (!state->needsSave) {
stateCond.wait(state.getUniqueLock());
}
do_save = state->needsSave;
state->needsSave = false;
}
if (do_save) {
do_state_save();
}
}
}
void w_state_shutdown(void) {
if (dont_save_state) {
return;
}
stateCond.notify_one();
state_saver_thread.join();
}
bool w_state_load(void)
{
json_error_t err;
if (dont_save_state) {
return true;
}
state_saver_thread = std::thread(state_saver);
auto state = json_load_file(watchman_state_file, 0, &err);
if (!state) {
w_log(W_LOG_ERR, "failed to parse json from %s: %s\n",
watchman_state_file,
err.text);
return false;
}
if (!w_root_load_state(state)) {
return false;
}
return true;
}
#if defined(HAVE_MKOSTEMP) && defined(sun)
// Not guaranteed to be defined in stdlib.h
extern int mkostemp(char *, int);
#endif
std::unique_ptr<watchman_stream> w_mkstemp(char* templ) {
#if defined(_WIN32)
char *name = _mktemp(templ);
if (!name) {
return nullptr;
}
// Most annoying aspect of windows is the latency around
// file handle exclusivity. We could avoid this dumb loop
// by implementing our own mkostemp, but this is the most
// expedient option for the moment.
for (size_t attempts = 0; attempts < 10; ++attempts) {
auto stm = w_stm_open(name, O_RDWR | O_CLOEXEC | O_CREAT | O_TRUNC, 0600);
if (stm) {
return stm;
}
if (errno == EACCES) {
/* sleep override */ usleep(2000);
continue;
}
return nullptr;
}
return nullptr;
#else
FileDescriptor fd;
# ifdef HAVE_MKOSTEMP
fd = FileDescriptor(mkostemp(templ, O_CLOEXEC));
# else
fd = FileDescriptor(mkstemp(templ));
# endif
if (!fd) {
return nullptr;
}
fd.setCloExec();
return w_stm_fdopen(std::move(fd));
#endif
}
static bool do_state_save(void) {
w_jbuffer_t buffer;
auto state = json_object();
auto file =
w_stm_open(watchman_state_file, O_WRONLY | O_TRUNC | O_CREAT, 0600);
if (!file) {
w_log(
W_LOG_ERR,
"save_state: unable to open %s for write: %s\n",
watchman_state_file,
strerror(errno));
return false;
}
state.set("version", typed_string_to_json(PACKAGE_VERSION, W_STRING_UNICODE));
/* now ask the different subsystems to fill out the state */
if (!w_root_save_state(state)) {
return false;
}
/* we've prepared what we're going to save, so write it out */
buffer.jsonEncodeToStream(state, file.get(), JSON_INDENT(4));
return true;
}
/** Arranges for the state to be saved.
* Does not immediately save the state. */
void w_state_save(void) {
if (dont_save_state) {
return;
}
saveState.wlock()->needsSave = true;
stateCond.notify_one();
}
/* vim:ts=2:sw=2:et:
*/
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