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Mutex Conditional
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* Improve `webui_wait()` by using mutex conditional signal instead of `sleep()` as suggested by @GiuseppeCesarano
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@hassandraga
hassandraga committed Aug 20, 2023
1 parent 78da533 commit 68a5d48
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Showing 2 changed files with 92 additions and 22 deletions.
104 changes: 82 additions & 22 deletions src/webui.c
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Original file line number Diff line number Diff line change
Expand Up @@ -437,6 +437,8 @@ bool webui_show(size_t window, const char* content) {
printf("[User] webui_show([%zu])...\n", window);
#endif

_webui_core.ui = true;

// Dereference
if(_webui_core.wins[window] == NULL) return false;
_webui_window_t* win = _webui_core.wins[window];
Expand Down Expand Up @@ -833,6 +835,9 @@ void webui_exit(void) {
// Let's give other threads more time to
// safely exit and finish their cleaning up.
_webui_sleep(120);

// Fire the mutex condition wait
_webui_condition_signal(&_webui_core.condition_wait);
}

void webui_wait(void) {
Expand All @@ -845,40 +850,42 @@ void webui_wait(void) {

if(_webui_core.startup_timeout > 0) {

#ifdef WEBUI_LOG
printf("[Loop] webui_wait() -> Using timeout %zu second\n", _webui_core.startup_timeout);
#endif

// Wait for browser to start
_webui_wait_for_startup();
// Check if there is atleast one window (UI)
// is running. Otherwise the mutex condition
// signal will never come
if(!_webui_core.ui)
return;

#ifdef WEBUI_LOG
printf("[Loop] webui_wait() -> Wait for connected UI...\n");
printf("[Loop] webui_wait() -> Timeout in %zu seconds\n", _webui_core.startup_timeout);
printf("[Loop] webui_wait() -> Waiting for connected UI...\n");
#endif

while(_webui_core.servers > 0) {

#ifdef WEBUI_LOG
// printf("[%zu/%zu]", _webui_core.servers, _webui_core.connections);
#endif
_webui_sleep(50);
}
// The mutex conditional signal will
// be fired when no more UI (servers)
// is running.
}
else {

#ifdef WEBUI_LOG
printf("[Loop] webui_wait() -> Infinite wait...\n");
#endif

// Infinite wait
while(!_webui_core.exit_now)
_webui_sleep(50);
// The mutex conditional signal will
// be fired when `webui_exit()` is
// called by the user.
}

// Waiting for the mutex conditional signal
_webui_mutex_lock(&_webui_core.mutex_wait);
_webui_condition_wait(&_webui_core.condition_wait, &_webui_core.mutex_wait);

#ifdef WEBUI_LOG
printf("[Loop] webui_wait() -> Wait finished.\n");
printf("[Loop] webui_wait() -> Wait is finished.\n");
#endif

_webui_mutex_unlock(&_webui_core.mutex_wait);

// Final cleaning
_webui_clean();
}
Expand Down Expand Up @@ -1786,7 +1793,43 @@ static const char* _webui_interpret_command(const char* cmd) {
return (const char*)out;
}

void _webui_mutex_init(webui_mutex_t *mutex) {
static void _webui_condition_init(webui_condition_t *cond) {

#ifdef _WIN32
InitializeConditionVariable(cond);
#else
pthread_cond_init(cond, NULL);
#endif
}

static void _webui_condition_wait(webui_condition_t *cond, webui_mutex_t *mutex) {

#ifdef _WIN32
SleepConditionVariableCS(cond, mutex, INFINITE);
#else
pthread_cond_wait(cond, mutex);
#endif
}

static void _webui_condition_signal(webui_condition_t *cond) {

#ifdef _WIN32
WakeConditionVariable(cond);
#else
pthread_cond_signal(cond);
#endif
}

static void _webui_condition_destroy(webui_condition_t *cond) {

#ifdef _WIN32
// No need
#else
pthread_cond_destroy(cond);
#endif
}

static void _webui_mutex_init(webui_mutex_t *mutex) {

#ifdef _WIN32
InitializeCriticalSection(mutex);
Expand All @@ -1795,7 +1838,7 @@ void _webui_mutex_init(webui_mutex_t *mutex) {
#endif
}

void _webui_mutex_lock(webui_mutex_t *mutex) {
static void _webui_mutex_lock(webui_mutex_t *mutex) {

#ifdef _WIN32
EnterCriticalSection(mutex);
Expand All @@ -1804,7 +1847,7 @@ void _webui_mutex_lock(webui_mutex_t *mutex) {
#endif
}

void _webui_mutex_unlock(webui_mutex_t *mutex) {
static void _webui_mutex_unlock(webui_mutex_t *mutex) {

#ifdef _WIN32
LeaveCriticalSection(mutex);
Expand All @@ -1813,7 +1856,7 @@ void _webui_mutex_unlock(webui_mutex_t *mutex) {
#endif
}

void _webui_mutex_destroy(webui_mutex_t *mutex) {
static void _webui_mutex_destroy(webui_mutex_t *mutex) {

#ifdef _WIN32
DeleteCriticalSection(mutex);
Expand Down Expand Up @@ -2846,6 +2889,17 @@ static void _webui_clean(void) {

// Free all non-freed memory allocations
_webui_free_all_mem();

// Destroy all mutex
_webui_mutex_destroy(&_webui_core.mutex_server_start);
_webui_mutex_destroy(&_webui_core.mutex_send);
_webui_mutex_destroy(&_webui_core.mutex_receive);
_webui_mutex_destroy(&_webui_core.mutex_wait);
_webui_condition_destroy(&_webui_core.condition_wait);

#ifdef WEBUI_LOG
printf("[Core]\t\tDone.\n");
#endif
}

static int _webui_cmd_sync(_webui_window_t* win, char* cmd, bool show) {
Expand Down Expand Up @@ -4139,6 +4193,8 @@ static void _webui_init(void) {
_webui_mutex_init(&_webui_core.mutex_server_start);
_webui_mutex_init(&_webui_core.mutex_send);
_webui_mutex_init(&_webui_core.mutex_receive);
_webui_mutex_init(&_webui_core.mutex_wait);
_webui_condition_init(&_webui_core.condition_wait);
}

static size_t _webui_get_cb_index(char* webui_internal_id) {
Expand Down Expand Up @@ -4944,6 +5000,10 @@ static WEBUI_SERVER_START
mg_stop(ws_ctx);
mg_stop(http_ctx);

// Fire the mutex condition wait
if(_webui_core.startup_timeout > 0 && _webui_core.servers < 1)
_webui_condition_signal(&_webui_core.condition_wait);

THREAD_RETURN
}

Expand Down
10 changes: 10 additions & 0 deletions src/webui_core.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,8 +32,10 @@
// Mutex
#ifdef _WIN32
typedef CRITICAL_SECTION webui_mutex_t;
typedef CONDITION_VARIABLE webui_condition_t;
#else
typedef pthread_mutex_t webui_mutex_t;
typedef pthread_cond_t webui_condition_t;
#endif

// Timer
Expand Down Expand Up @@ -109,6 +111,9 @@ typedef struct _webui_core_t {
webui_mutex_t mutex_server_start;
webui_mutex_t mutex_send;
webui_mutex_t mutex_receive;
webui_mutex_t mutex_wait;
webui_condition_t condition_wait;
bool ui;
} _webui_core_t;

typedef struct _webui_cb_arg_t {
Expand Down Expand Up @@ -204,10 +209,15 @@ static void _webui_print_ascii(const char* data, size_t len);
static void _webui_panic(void);
static void _webui_kill_pid(size_t pid);
static _webui_window_t* _webui_dereference_win_ptr(void* ptr);

static void _webui_mutex_init(webui_mutex_t *mutex);
static void _webui_mutex_lock(webui_mutex_t *mutex);
static void _webui_mutex_unlock(webui_mutex_t *mutex);
static void _webui_mutex_destroy(webui_mutex_t *mutex);
static void _webui_condition_init(webui_condition_t *cond);
static void _webui_condition_wait(webui_condition_t *cond, webui_mutex_t *mutex);
static void _webui_condition_signal(webui_condition_t *cond);
static void _webui_condition_destroy(webui_condition_t *cond);

static void _webui_http_send(struct mg_connection *conn, const char* mime_type, const char* body);
static void _webui_http_send_error_page(struct mg_connection *conn, const char* body, int status);
Expand Down

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