commit 2b4f3de

replace semaphore.h with slot tracking

  1@@ -10,7 +10,6 @@
  2 
  3 #include <errno.h>
  4 #include <fcntl.h>
  5-#include <semaphore.h>
  6 #include <signal.h>
  7 #include <stdarg.h>
  8 #include <stdbool.h>
  9@@ -43,15 +42,18 @@ static void apply_rlimits(void);
 10 static int client_thread(void* arg);
 11 static void fd_set_cloexec(int fd);
 12 static void sock_set_timeouts(int fd);
 13+static void release_slot(void);
 14+static int try_acquire_slot(void);
 15 
 16 void die(const char* s, int e);
 17 void run(void);
 18 void setup(void);
 19 
 20-static sem_t slots;
 21 static int sock;
 22 struct library lib;
 23 mtx_t lib_lock;
 24+static mtx_t slots_lock;
 25+static int slots_available;
 26 
 27 static void apply_rlimits(void)
 28 {
 29@@ -75,7 +77,7 @@ static int client_thread(void* arg)
 30 	shutdown(c, SHUT_WR);
 31 	close(c);
 32 
 33-	(void)sem_post(&slots);
 34+	release_slot();
 35 	return 0;
 36 }
 37 
 38@@ -96,6 +98,33 @@ static void sock_set_timeouts(int fd)
 39 	(void)setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
 40 }
 41 
 42+static void release_slot(void)
 43+{
 44+	if (mtx_lock(&slots_lock) != thrd_success)
 45+		return;
 46+
 47+	if (slots_available < max_clients)
 48+		slots_available++;
 49+
 50+	(void)mtx_unlock(&slots_lock);
 51+}
 52+
 53+static int try_acquire_slot(void)
 54+{
 55+	int ok = 0;
 56+
 57+	if (mtx_lock(&slots_lock) != thrd_success)
 58+		return -1;
 59+
 60+	if (slots_available > 0) {
 61+		slots_available--;
 62+		ok = 1;
 63+	}
 64+
 65+	(void)mtx_unlock(&slots_lock);
 66+	return ok;
 67+}
 68+
 69 void die(const char* s, int e)
 70 {
 71 	perror(s);
 72@@ -117,7 +146,7 @@ void run(void)
 73 		fd_set_cloexec(c);
 74 
 75 		/* client cap. if full 503 and close */
 76-		if (sem_trywait(&slots) < 0) {
 77+		if (try_acquire_slot() != 1) {
 78 			/* short 503 + retry after */
 79 			static const char resp[] =
 80 				"HTTP/1.1 503 Service Unavailable\r\n"
 81@@ -140,7 +169,7 @@ void run(void)
 82 		if (err != thrd_success) {
 83 			LOG(true, "CORE", "thrd_create FAILED  %d", err);
 84 			close(c);
 85-			(void)sem_post(&slots);
 86+			release_slot();
 87 			continue;
 88 		}
 89 
 90@@ -158,8 +187,9 @@ void setup(void)
 91 	if (mtx_init(&lib_lock, mtx_plain) != thrd_success)
 92 		die("mtx_init", EXIT_FAILURE);
 93 
 94-	if (sem_init(&slots, 0, max_clients) < 0)
 95-		die("sem_init", EXIT_FAILURE);
 96+	if (mtx_init(&slots_lock, mtx_plain) != thrd_success)
 97+		die("mtx_init", EXIT_FAILURE);
 98+	slots_available = max_clients;
 99 
100 	int ret = 1;
101 	sock = socket(AF_INET, SOCK_STREAM, 0);