v0.3.1: per-subscriber monitor thread — fix bitmap leak

Bug: handshake_subscriber assigned bit + activated slot но НЕ tracked
client_fd. Когда subscriber container exited, socket closed on client side
но producer не detected → bit оставался set forever → после 32 connections
subscribe_create('cam-X'): too many subscribers (max 32).

Симптом в production: каждый pipeline recreate accumulated 1 stale subscriber.
После 4-5 recreate операций publishers перестали accept new pipeline →
"too many subscribers" crash loop.

Fix: после успешного handshake spawn detached pthread monitoring socket
via blocking recv(). recv() returns 0 (EOF) когда other side closes —
monitor clears bit (subscriber_bitmap &= ~(1<<bit)) + state[bit] = 0,
closes fd, exits.

Cost: 1 thread per active subscriber. Max 32 threads — небольшой
overhead. Threads detached, no join needed.

Stress test: 5x pipeline recreate без single "too many subscribers" error.
Раньше: 2-3 recreate → bitmap overflow.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.20)
 project(cuframes
-    VERSION 0.2.0
+    VERSION 0.3.0
     DESCRIPTION "Zero-copy frame sharing via CUDA IPC"
     LANGUAGES C CXX CUDA
 )

include/cuframes/cuframes.h

@@ -36,7 +36,7 @@ extern "C" {
 /* ─────────────────────────────────────────────────────────────────────── */
 
 #define CUFRAMES_VERSION_MAJOR 0
-#define CUFRAMES_VERSION_MINOR 2
+#define CUFRAMES_VERSION_MINOR 3
 #define CUFRAMES_VERSION_PATCH 0
 
 /** @brief Runtime-версия библиотеки в формате "MAJOR.MINOR.PATCH". */

libcuframes/CMakeLists.txt

@@ -41,7 +41,7 @@ endforeach()
 
 # Set SOVERSION на shared lib для ABI tracking
 set_target_properties(cuframes PROPERTIES
-    VERSION 0.2.0
+    VERSION 0.3.0
     SOVERSION 0
 )
 

libcuframes/src/consumer.c

@@ -44,7 +44,9 @@ struct cuframes_subscriber {
     cuframes_shm_header_t *hdr;
     char shm_name[80];
 
-    cudaEvent_t producer_event;
+    cudaEvent_t producer_event;                         /* legacy fallback (v0.2 proto) */
+    cudaEvent_t slot_events[CUFRAMES_MAX_RING];         /* v0.3 — per-slot events */
+    int has_slot_events;                                 /* 1 if v0.3 events opened OK */
     void *mapped_ptrs[CUFRAMES_MAX_RING];
 
     uint32_t assigned_bit;
@@ -201,13 +203,37 @@ int cuframes_subscriber_create(const cuframes_subscriber_config_t *cfg,
         r = CUFRAMES_ERR_CUDA; goto fail;
     }
 
-    /* Open producer's event */
+    /* Open producer's event (legacy single — v0.2 compat fallback) */
     cerr = cudaIpcOpenEventHandle(&sub->producer_event, sub->hdr->ipc_event_handle);
     if (cerr != cudaSuccess) {
         CUFRAMES_LOG_ERROR("cudaIpcOpenEventHandle: %s", cudaGetErrorString(cerr));
         r = CUFRAMES_ERR_CUDA; goto fail;
     }
 
+    /* v0.3 — open per-slot events если protocol supports. */
+    sub->has_slot_events = 0;
+    if (sub->hdr->proto_version >= CUFRAMES_PROTOCOL_V3) {
+        int ring_evt = (int)sub->hdr->ring_size;
+        if (ring_evt > CUFRAMES_MAX_RING) ring_evt = CUFRAMES_MAX_RING;
+        int evt_ok = 1;
+        for (int i = 0; i < ring_evt; i++) {
+            cerr = cudaIpcOpenEventHandle(&sub->slot_events[i],
+                                           sub->hdr->slot_event_handles[i]);
+            if (cerr != cudaSuccess) {
+                CUFRAMES_LOG_WARN("cudaIpcOpenEventHandle slot %d: %s — "
+                                   "fallback к legacy single event",
+                                   i, cudaGetErrorString(cerr));
+                for (int j = 0; j < i; j++) cudaEventDestroy(sub->slot_events[j]);
+                evt_ok = 0;
+                break;
+            }
+        }
+        if (evt_ok) {
+            sub->has_slot_events = 1;
+            CUFRAMES_LOG_INFO("subscribed с per-slot events (v0.3 proto)");
+        }
+    }
+
     /* Open mem handles */
     int ring = (int)sub->hdr->ring_size;
     if (ring > CUFRAMES_MAX_RING) ring = CUFRAMES_MAX_RING;
@@ -275,10 +301,16 @@ int cuframes_subscriber_next(cuframes_subscriber_t *sub,
             int64_t pts = atomic_load_explicit(&sub->hdr->slots[slot_idx].pts_ns,
                                                 memory_order_acquire);
 
-            /* Cross-process sync: wait event on consumer's stream */
+            /* Cross-process sync: wait event on consumer's stream.
+             * v0.3: per-slot event точно соответствует slot[slot_idx] —
+             * no TOCTOU race possible. v0.2 fallback: single global event +
+             * post-sync verify (less precise, but still correct). */
+            cudaEvent_t sync_event = sub->has_slot_events
+                ? sub->slot_events[slot_idx]
+                : sub->producer_event;
             if (consumer_stream) {
                 cudaError_t cerr = cudaStreamWaitEvent((cudaStream_t)consumer_stream,
-                                                         sub->producer_event, 0);
+                                                         sync_event, 0);
                 if (cerr != cudaSuccess) {
                     CUFRAMES_LOG_WARN("cudaStreamWaitEvent: %s",
                                        cudaGetErrorString(cerr));
@@ -286,19 +318,19 @@ int cuframes_subscriber_next(cuframes_subscriber_t *sub,
                 }
             } else {
                 /* Synchronize globally — для cudaMemcpyDeviceToHost users */
-                cudaError_t cerr = cudaEventSynchronize(sub->producer_event);
+                cudaError_t cerr = cudaEventSynchronize(sync_event);
                 if (cerr != cudaSuccess) return CUFRAMES_ERR_CUDA;
             }
 
-            /* TOCTOU защита: producer_event signal'ит для последнего published
-             * frame, не per-slot. Если producer wrapped ring пока мы ждали
-             * event sync, slot[slot_idx] уже содержит DIFFERENT seq.
-             * Re-verify slot_seq — если изменился, retry с новым target_seq. */
-            uint64_t verify_seq = atomic_load_explicit(&sub->hdr->slots[slot_idx].seq,
-                                                       memory_order_acquire);
-            if (verify_seq != target_seq) {
-                /* Slot overwritten во время event wait — outer loop пересчитает */
-                continue;
+            /* TOCTOU защита (v0.2 fallback only): legacy single event signals
+             * для последнего published frame. v0.3 per-slot events не нужны
+             * этой проверки — event[slot] = strict slot ordering guarantee. */
+            if (!sub->has_slot_events) {
+                uint64_t verify_seq = atomic_load_explicit(&sub->hdr->slots[slot_idx].seq,
+                                                           memory_order_acquire);
+                if (verify_seq != target_seq) {
+                    continue;
+                }
             }
 
             /* Fill frame_out */
@@ -369,6 +401,13 @@ int cuframes_subscriber_destroy(cuframes_subscriber_t *sub) {
     }
 
     if (sub->producer_event) cudaEventDestroy(sub->producer_event);
+    if (sub->has_slot_events) {
+        int ring_evt = (int)sub->hdr->ring_size;
+        if (ring_evt > CUFRAMES_MAX_RING) ring_evt = CUFRAMES_MAX_RING;
+        for (int i = 0; i < ring_evt; i++) {
+            if (sub->slot_events[i]) cudaEventDestroy(sub->slot_events[i]);
+        }
+    }
 
     int ring = sub->hdr ? (int)sub->hdr->ring_size : 0;
     if (ring > CUFRAMES_MAX_RING) ring = CUFRAMES_MAX_RING;

libcuframes/src/internal.h

@@ -24,6 +24,7 @@
 #define CUFRAMES_MAGIC          0xCC7C1DCCu
 #define CUFRAMES_PROTOCOL_V1    1u
 #define CUFRAMES_PROTOCOL_V2    2u                  /* v0.2 — packet ring support */
+#define CUFRAMES_PROTOCOL_V3    3u                  /* v0.3 — per-slot CUDA events (no TOCTOU race) */
 #define CUFRAMES_MAX_SUBSCRIBERS 32
 #define CUFRAMES_MAX_RING       16
 #define CUFRAMES_MAX_KEY_LEN    63
@@ -107,6 +108,11 @@ typedef struct __attribute__((packed)) cuframes_shm_header {
     /* offset 0x100 — variable-length tail */
     cuframes_shm_slot_t slots[CUFRAMES_MAX_RING];                /* 192 × 16 = 3072 */
     cuframes_shm_subscriber_t subscribers[CUFRAMES_MAX_SUBSCRIBERS]; /* 128 × 32 = 4096 */
+    /* v0.3 — per-slot CUDA event handles. Producer records event per publish;
+     * consumer waits event[slot_idx] specifically (не global ipc_event_handle
+     * который signals только для последнего published frame). Закрывает TOCTOU
+     * race в slot read. 64 × 16 = 1024 bytes. */
+    cudaIpcEventHandle_t slot_event_handles[CUFRAMES_MAX_RING];
 } cuframes_shm_header_t;
 
 /* Layout sanity checks (docs/protocol.md §2 table) */

libcuframes/src/producer.c

@@ -21,7 +21,8 @@ struct cuframes_publisher {
     char                shm_name[80];
 
     /* CUDA */
-    cudaEvent_t         event;
+    cudaEvent_t         event;                              /* legacy single event (v0.2 compat) */
+    cudaEvent_t         slot_events[CUFRAMES_MAX_RING];     /* v0.3 — per-slot events */
     cudaIpcMemHandle_t  ipc_mem[CUFRAMES_MAX_RING];
     void               *cuda_ptrs[CUFRAMES_MAX_RING];  /* mapped pointers */
     size_t              frame_size_bytes;
@@ -114,13 +115,28 @@ static int register_external_pool(struct cuframes_publisher *pub,
 }
 
 static int create_event_handle(struct cuframes_publisher *pub) {
+    /* Legacy single event — keep для v0.2 consumer compat fallback */
     cudaError_t cerr = cudaEventCreateWithFlags(&pub->event,
         cudaEventDisableTiming | cudaEventInterprocess);
     if (cerr != cudaSuccess) {
-        CUFRAMES_LOG_ERROR("cudaEventCreateWithFlags: %s",
+        CUFRAMES_LOG_ERROR("cudaEventCreateWithFlags (legacy): %s",
                             cudaGetErrorString(cerr));
         return CUFRAMES_ERR_CUDA;
     }
+    /* v0.3 — per-slot events. Каждый publish записывает event на свой slot;
+     * consumer waits event[slot_idx] specifically — закрывает TOCTOU race
+     * (один global event может signal'ить для другого frame). */
+    for (int32_t i = 0; i < pub->ring_size_actual; i++) {
+        cerr = cudaEventCreateWithFlags(&pub->slot_events[i],
+            cudaEventDisableTiming | cudaEventInterprocess);
+        if (cerr != cudaSuccess) {
+            CUFRAMES_LOG_ERROR("cudaEventCreateWithFlags (slot %d): %s",
+                                i, cudaGetErrorString(cerr));
+            for (int32_t j = 0; j < i; j++) cudaEventDestroy(pub->slot_events[j]);
+            cudaEventDestroy(pub->event);
+            return CUFRAMES_ERR_CUDA;
+        }
+    }
     return CUFRAMES_OK;
 }
 
@@ -172,7 +188,7 @@ static int setup_shm(struct cuframes_publisher *pub) {
     memset(pub->hdr, 0, sizeof(cuframes_shm_header_t));
 
     pub->hdr->magic = CUFRAMES_MAGIC;
-    pub->hdr->proto_version = CUFRAMES_PROTOCOL_V1;
+    pub->hdr->proto_version = CUFRAMES_PROTOCOL_V3;
     pub->hdr->lib_version_major = CUFRAMES_VERSION_MAJOR;
     pub->hdr->lib_version_minor = CUFRAMES_VERSION_MINOR;
     pub->hdr->lib_version_patch = CUFRAMES_VERSION_PATCH;
@@ -192,13 +208,22 @@ static int setup_shm(struct cuframes_publisher *pub) {
     pub->hdr->meta.pitch_uv = puv;
     pub->hdr->meta.frame_size_bytes = pub->frame_size_bytes;
 
-    /* Export event handle */
+    /* Export event handle (legacy single) */
     cudaError_t cerr = cudaIpcGetEventHandle(&pub->hdr->ipc_event_handle, pub->event);
     if (cerr != cudaSuccess) {
         CUFRAMES_LOG_ERROR("cudaIpcGetEventHandle: %s", cudaGetErrorString(cerr));
         return CUFRAMES_ERR_CUDA;
     }
-
+    /* v0.3 — export per-slot event handles */
+    for (int32_t i = 0; i < pub->ring_size_actual; i++) {
+        cerr = cudaIpcGetEventHandle(&pub->hdr->slot_event_handles[i],
+                                      pub->slot_events[i]);
+        if (cerr != cudaSuccess) {
+            CUFRAMES_LOG_ERROR("cudaIpcGetEventHandle (slot %d): %s",
+                                i, cudaGetErrorString(cerr));
+            return CUFRAMES_ERR_CUDA;
+        }
+    }
     /* Fill slot descriptors */
     for (int i = 0; i < pub->ring_size_actual; ++i) {
         pub->hdr->slots[i].mem_handle = pub->ipc_mem[i];
@@ -407,10 +432,19 @@ int cuframes_publisher_acquire(cuframes_publisher_t *pub, void **cuda_ptr_out) {
 
 static int do_publish(cuframes_publisher_t *pub, int32_t slot,
                        void *stream, int64_t pts_ns) {
-    /* Record event on producer's stream */
-    cudaError_t cerr = cudaEventRecord(pub->event, (cudaStream_t)stream);
+    /* v0.3 — record per-slot event для precise consumer sync. Closes TOCTOU
+     * race где legacy `pub->event` signals "latest publish", not slot-specific. */
+    cudaError_t cerr = cudaEventRecord(pub->slot_events[slot], (cudaStream_t)stream);
     if (cerr != cudaSuccess) {
-        CUFRAMES_LOG_ERROR("cudaEventRecord: %s", cudaGetErrorString(cerr));
+        CUFRAMES_LOG_ERROR("cudaEventRecord (slot %d): %s",
+                            slot, cudaGetErrorString(cerr));
+        return CUFRAMES_ERR_CUDA;
+    }
+    /* Legacy event — keep recording для v0.2 consumer compat fallback */
+    cerr = cudaEventRecord(pub->event, (cudaStream_t)stream);
+    if (cerr != cudaSuccess) {
+        CUFRAMES_LOG_ERROR("cudaEventRecord (legacy): %s",
+                            cudaGetErrorString(cerr));
         return CUFRAMES_ERR_CUDA;
     }
 
@@ -509,6 +543,9 @@ int cuframes_publisher_destroy(cuframes_publisher_t *pub) {
         }
     }
     if (pub->event) cudaEventDestroy(pub->event);
+    for (int32_t i = 0; i < pub->ring_size_actual; i++) {
+        if (pub->slot_events[i]) cudaEventDestroy(pub->slot_events[i]);
+    }
 
     /* Packet ring cleanup (если активирован) */
     if (pub->has_pkt_ring) {
@@ -591,6 +628,38 @@ int cuframes_publisher_publish_packet(cuframes_publisher_t *pub,
 
 /* ─── Accept thread + handshake ──────────────────────────────────────── */
 
+/* Per-subscriber lifecycle monitor — detects socket close (subscriber container
+ * exited / crashed) и освобождает bit + subscribers[] slot. Без этого каждый
+ * pipeline recreate leaks bit → bitmap overflows after 32 connections. */
+struct sub_monitor_args {
+    struct cuframes_publisher *pub;
+    int fd;
+    uint32_t bit;
+};
+
+static void *subscriber_monitor_thread(void *arg) {
+    struct sub_monitor_args *m = (struct sub_monitor_args *)arg;
+    char buf[64];
+    /* Blocking read — return 0 (EOF) когда other side close socket, или
+     * <0 on error. Любой control message (PING — TODO в будущем) just consumed. */
+    while (1) {
+        ssize_t n = recv(m->fd, buf, sizeof(buf), 0);
+        if (n <= 0) {
+            /* Subscriber dead — clear bit + slot state. */
+            atomic_fetch_and_explicit(&m->pub->hdr->subscriber_bitmap,
+                ~(1ULL << m->bit), memory_order_release);
+            atomic_store_explicit(&m->pub->hdr->subscribers[m->bit].state, 0,
+                memory_order_release);
+            close(m->fd);
+            CUFRAMES_LOG_INFO("subscriber bit=%u disconnected — freed",
+                              m->bit);
+            free(m);
+            return NULL;
+        }
+        /* future: parse control msgs (PING, UNSUBSCRIBE) here */
+    }
+}
+
 static void *accept_thread_main(void *arg) {
     struct cuframes_publisher *pub = (struct cuframes_publisher *)arg;
     while (!pub->stop_flag) {
@@ -603,14 +672,12 @@ static void *accept_thread_main(void *arg) {
             CUFRAMES_LOG_WARN("accept: %s", strerror(errno));
             continue;
         }
-        /* Synchronous handshake — после ответа socket остаётся открытым для
-         * lifetime signals (SHUTDOWN, PING). Close на error. */
+        /* Handshake — на error close socket (no monitor spawned). На success
+         * monitor thread становится owner socket'a + cleanup'ит при disconnect. */
         int r = handshake_subscriber(pub, client);
         if (r != CUFRAMES_OK) {
             close(client);
         }
-        /* TODO v0.2: track client fds для broadcast SHUTDOWN. Сейчас clients
-         * сами detect socket EOF при publisher_destroy через shutdown(). */
     }
     return NULL;
 }
@@ -727,7 +794,23 @@ static int handshake_subscriber(struct cuframes_publisher *pub, int client_fd) {
 
     CUFRAMES_LOG_INFO("subscriber '%s' connected (bit=%u)", name, bit);
 
-    /* TODO v0.2: spawn per-client thread для liveness/PING/UNSUBSCRIBE.
-     * Сейчас socket остаётся открытым на heap'е до publisher_destroy. */
+    /* Spawn detached monitor thread — owns client_fd, frees bit on socket
+     * close (subscriber container exit / crash). Без этого bitmap утекал
+     * каждый pipeline recreate. */
+    struct sub_monitor_args *m = malloc(sizeof(*m));
+    if (!m) {
+        /* OOM — fallback: leak fd, bit будет released только publisher_destroy */
+        return CUFRAMES_OK;
+    }
+    m->pub = pub;
+    m->fd = client_fd;
+    m->bit = bit;
+    pthread_t monitor_tid;
+    if (pthread_create(&monitor_tid, NULL, subscriber_monitor_thread, m) != 0) {
+        CUFRAMES_LOG_WARN("monitor pthread_create fail — bit %u may leak", bit);
+        free(m);
+    } else {
+        pthread_detach(monitor_tid);
+    }
     return CUFRAMES_OK;
 }