Replace pointer comparison with envelope tag in retry seal check

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jpnurmi

src/sentry_envelope.c

@@ -7,6 +7,7 @@
 #include "sentry_ratelimiter.h"
 #include "sentry_scope.h"
 #include "sentry_string.h"
+#include "sentry_sync.h"
 #include "sentry_transport.h"
 #include "sentry_value.h"
 #include <assert.h>
@@ -21,7 +22,20 @@ struct sentry_envelope_item_s {
     sentry_envelope_item_t *next;
 };
 
+static long
+next_tag(void)
+{
+    static volatile long counter = 0;
+    long tag = sentry__atomic_fetch_and_add(&counter, 1);
+    if (tag == 0) {
+        // skip 0-sentinel on overflow
+        tag = sentry__atomic_fetch_and_add(&counter, 1);
+    }
+    return tag;
+}
+
 struct sentry_envelope_s {
+    long tag;
     bool is_raw;
     union {
         struct {
@@ -199,6 +213,7 @@ sentry__envelope_new_with_dsn(const sentry_dsn_t *dsn)
         return NULL;
     }
 
+    rv->tag = next_tag();
     rv->is_raw = false;
     rv->contents.items.first_item = NULL;
     rv->contents.items.last_item = NULL;
@@ -236,6 +251,12 @@ sentry__envelope_from_path(const sentry_path_t *path)
     return envelope;
 }
 
+long
+sentry__envelope_get_tag(const sentry_envelope_t *envelope)
+{
+    return envelope->tag;
+}
+
 sentry_uuid_t
 sentry__envelope_get_event_id(const sentry_envelope_t *envelope)
 {

src/sentry_envelope.h

@@ -31,6 +31,11 @@ sentry_envelope_t *sentry__envelope_new_with_dsn(const sentry_dsn_t *dsn);
  */
 sentry_envelope_t *sentry__envelope_from_path(const sentry_path_t *path);
 
+/**
+ * Returns a unique non-zero tag assigned at envelope creation.
+ */
+long sentry__envelope_get_tag(const sentry_envelope_t *envelope);
+
 /**
  * This returns the UUID of the event associated with this envelope.
  * If there is no event inside this envelope, the empty nil UUID will be

src/sentry_retry.c

@@ -35,7 +35,7 @@ struct sentry_retry_s {
     sentry_retry_send_func_t send_cb;
     void *send_data;
     sentry_mutex_t sealed_lock;
-    uintptr_t sealed_envelope;
+    long sealed_tag;
 };
 
 sentry_retry_t *
@@ -301,10 +301,10 @@ retry_dump_cb(void *_envelope, void *_retry)
 {
     sentry_retry_t *retry = (sentry_retry_t *)_retry;
     sentry_envelope_t *envelope = (sentry_envelope_t *)_envelope;
-    if ((uintptr_t)envelope != retry->sealed_envelope) {
+    if (sentry__envelope_get_tag(envelope) != retry->sealed_tag) {
         sentry__run_write_cache(retry->run, envelope, 0);
     } else {
-        retry->sealed_envelope = 0;
+        retry->sealed_tag = 0;
     }
     return true;
 }
@@ -350,7 +350,7 @@ sentry__retry_enqueue(sentry_retry_t *retry, const sentry_envelope_t *envelope)
         sentry__mutex_unlock(&retry->sealed_lock);
         return;
     }
-    retry->sealed_envelope = (uintptr_t)envelope;
+    retry->sealed_tag = sentry__envelope_get_tag(envelope);
     sentry__mutex_unlock(&retry->sealed_lock);
 
     sentry__atomic_compare_swap(