1 files changed, 70 insertions, 0 deletions

diff --git a/src/ot_mutex.c b/src/ot_mutex.c
new file mode 100644
index 0000000..884b74c
--- /dev/null
+++ b/src/ot_mutex.c
@@ -0,0 +1,70 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <arpa/inet.h>
+#include <pthread.h>
+#include <stdatomic.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/uio.h>
+
+
+/* Opentracker */
+#include "ot_iovec.h"
+#include "ot_mutex.h"
+#include "ot_stats.h"
+#include "trackerlogic.h"
+
+/* #define MTX_DBG( STRING ) fprintf( stderr, STRING ) */
+#define MTX_DBG(STRING)
+
+/* Our global all torrents list */
+static ot_vector       all_torrents[OT_BUCKET_COUNT];
+static pthread_mutex_t bucket_mutex[OT_BUCKET_COUNT];
+/* Every bucket's unlock adjusts this, and a bucket lock only keeps other
+   threads out of that one bucket, so the counter needs its own protection */
+static _Atomic size_t  g_torrent_count;
+
+ot_vector *mutex_bucket_lock(int bucket) {
+  pthread_mutex_lock(bucket_mutex + bucket);
+  return all_torrents + bucket;
+}
+
+/* Torrents are spread over buckets by the first four bytes of their info_hash,
+   which may sit at any alignment, hence the memcpy */
+static int bucket_from_hash(ot_hash const hash) {
+  uint32_t bucket;
+  memcpy(&bucket, hash, sizeof(bucket));
+  return ntohl(bucket) >> OT_BUCKET_COUNT_SHIFT;
+}
+
+ot_vector *mutex_bucket_lock_by_hash(ot_hash const hash) { return mutex_bucket_lock(bucket_from_hash(hash)); }
+
+void mutex_bucket_unlock(int bucket, int delta_torrentcount) {
+  pthread_mutex_unlock(bucket_mutex + bucket);
+  if (delta_torrentcount)
+    atomic_fetch_add_explicit(&g_torrent_count, (size_t)delta_torrentcount, memory_order_relaxed);
+}
+
+void mutex_bucket_unlock_by_hash(ot_hash const hash, int delta_torrentcount) {
+  mutex_bucket_unlock(bucket_from_hash(hash), delta_torrentcount);
+}
+
+size_t mutex_get_torrent_count(void) { return atomic_load_explicit(&g_torrent_count, memory_order_relaxed); }
+
+void mutex_init(void) {
+  size_t i;
+  for (i = 0; i < OT_BUCKET_COUNT; ++i)
+    pthread_mutex_init(bucket_mutex + i, NULL);
+  memset(all_torrents, 0, sizeof(all_torrents));
+}
+
+void mutex_deinit(void) {
+  size_t i;
+  for (i = 0; i < OT_BUCKET_COUNT; ++i)
+    pthread_mutex_destroy(bucket_mutex + i);
+  memset(all_torrents, 0, sizeof(all_torrents));
+}