ssb: Add support for registering for blob added notifications similarly to messages. I want to use this to load images on the fly.

src/ssb.c

@@ -133,6 +133,15 @@ typedef struct _tf_ssb_message_added_callback_node_t
 	tf_ssb_message_added_callback_node_t* next;
 } tf_ssb_message_added_callback_node_t;
 
+typedef struct _tf_ssb_blob_stored_callback_node_t tf_ssb_blob_stored_callback_node_t;
+typedef struct _tf_ssb_blob_stored_callback_node_t
+{
+	tf_ssb_blob_stored_callback_t* callback;
+	tf_ssb_callback_cleanup_t* cleanup;
+	void* user_data;
+	tf_ssb_blob_stored_callback_node_t* next;
+} tf_ssb_blob_stored_callback_node_t;
+
 typedef struct _tf_ssb_blob_want_added_callback_node_t tf_ssb_blob_want_added_callback_node_t;
 typedef struct _tf_ssb_blob_want_added_callback_node_t
 {
@@ -235,6 +244,9 @@ typedef struct _tf_ssb_t
 	tf_ssb_message_added_callback_node_t* message_added;
 	int message_added_count;
 
+	tf_ssb_blob_stored_callback_node_t* blob_stored;
+	int blob_stored_count;
+
 	tf_ssb_blob_want_added_callback_node_t* blob_want_added;
 	int blob_want_added_count;
 
@@ -2741,6 +2753,17 @@ void tf_ssb_destroy(tf_ssb_t* ssb)
 		}
 		tf_free(node);
 	}
+	while (ssb->blob_stored)
+	{
+		tf_ssb_blob_stored_callback_node_t* node = ssb->blob_stored;
+		ssb->blob_stored = node->next;
+		ssb->blob_stored_count--;
+		if (node->cleanup)
+		{
+			node->cleanup(ssb, node->user_data);
+		}
+		tf_free(node);
+	}
 	while (ssb->blob_want_added)
 	{
 		tf_ssb_blob_want_added_callback_node_t* node = ssb->blob_want_added;
@@ -3960,9 +3983,53 @@ void tf_ssb_remove_message_added_callback(tf_ssb_t* ssb, tf_ssb_message_added_ca
 	}
 }
 
+void tf_ssb_add_blob_stored_callback(tf_ssb_t* ssb, tf_ssb_blob_stored_callback_t* callback, void (*cleanup)(tf_ssb_t* ssb, void* user_data), void* user_data)
+{
+	tf_ssb_blob_stored_callback_node_t* node = tf_malloc(sizeof(tf_ssb_blob_stored_callback_node_t));
+	*node = (tf_ssb_blob_stored_callback_node_t) {
+		.callback = callback,
+		.cleanup = cleanup,
+		.user_data = user_data,
+		.next = ssb->blob_stored,
+	};
+	ssb->blob_stored = node;
+	ssb->blob_stored_count++;
+}
+
+void tf_ssb_remove_blob_stored_callback(tf_ssb_t* ssb, tf_ssb_blob_stored_callback_t* callback, void* user_data)
+{
+	tf_ssb_blob_stored_callback_node_t** it = &ssb->blob_stored;
+	while (*it)
+	{
+		if ((*it)->callback == callback && (*it)->user_data == user_data)
+		{
+			tf_ssb_blob_stored_callback_node_t* node = *it;
+			*it = node->next;
+			ssb->blob_stored_count--;
+			if (node->cleanup)
+			{
+				node->cleanup(ssb, node->user_data);
+			}
+			tf_free(node);
+		}
+		else
+		{
+			it = &(*it)->next;
+		}
+	}
+}
+
 void tf_ssb_notify_blob_stored(tf_ssb_t* ssb, const char* id)
 {
+	tf_ssb_blob_stored_callback_node_t* next = NULL;
 	ssb->blobs_stored++;
+	for (tf_ssb_blob_stored_callback_node_t* node = ssb->blob_stored; node; node = next)
+	{
+		next = node->next;
+		tf_trace_begin(ssb->trace, "blob stored callback");
+		node->callback(ssb, id, node->user_data);
+		tf_trace_end(ssb->trace);
+	}
 }
 
 void tf_ssb_notify_message_added(tf_ssb_t* ssb, const char* author, int32_t sequence, const char* id, JSValue message_keys)

src/ssb.h

@@ -680,6 +680,31 @@ void tf_ssb_remove_message_added_callback(tf_ssb_t* ssb, tf_ssb_message_added_ca
 */
 void tf_ssb_notify_message_added(tf_ssb_t* ssb, const char* author, int32_t sequence, const char* id, JSValue message_with_keys);
 
+/**
+** A callback called when a blob is added to the database.
+** @param ssb The SSB instance.
+** @param id The blob identifier.
+** @param user_data The user data.
+*/
+typedef void(tf_ssb_blob_stored_callback_t)(tf_ssb_t* ssb, const char* id, void* user_data);
+
+/**
+** Register a callback called when a blob is added to the database.
+** @param ssb The SSB instance.
+** @param callback The callback function.
+** @param cleanup A function to call when the callback is removed.
+** @param user_data User data to pass to the callback.
+*/
+void tf_ssb_add_blob_stored_callback(tf_ssb_t* ssb, tf_ssb_blob_stored_callback_t* callback, tf_ssb_callback_cleanup_t* cleanup, void* user_data);
+
+/**
+** Remove a callback registered for when a blob is added to the database.
+** @param ssb The SSB instance.
+** @param callback The callback function.
+** @param user_data User data registered with the callback.
+*/
+void tf_ssb_remove_blob_stored_callback(tf_ssb_t* ssb, tf_ssb_blob_stored_callback_t* callback, void* user_data);
+
 /**
 ** Record that a new blob was stored.
 ** @param ssb The SSB instance.

src/ssb.js.c

@@ -1627,6 +1627,20 @@ static void _tf_ssb_on_message_added_callback(tf_ssb_t* ssb, const char* author,
 	JS_FreeValue(context, string);
 }
 
+static void _tf_ssb_on_blob_stored_callback(tf_ssb_t* ssb, const char* id, void* user_data)
+{
+	JSContext* context = tf_ssb_get_context(ssb);
+	JSValue callback = JS_MKPTR(JS_TAG_OBJECT, user_data);
+	JSValue string = JS_NewString(context, id);
+	JSValue response = JS_Call(context, callback, JS_UNDEFINED, 1, &string);
+	if (tf_util_report_error(context, response))
+	{
+		tf_ssb_remove_blob_stored_callback(ssb, _tf_ssb_on_blob_stored_callback, user_data);
+	}
+	JS_FreeValue(context, response);
+	JS_FreeValue(context, string);
+}
+
 static void _tf_ssb_on_blob_want_added_callback(tf_ssb_t* ssb, const char* id, void* user_data)
 {
 	JSContext* context = tf_ssb_get_context(ssb);
@@ -1747,6 +1761,11 @@ static JSValue _tf_ssb_add_event_listener(JSContext* context, JSValueConst this_
 			void* ptr = JS_VALUE_GET_PTR(JS_DupValue(context, callback));
 			tf_ssb_add_message_added_callback(ssb, _tf_ssb_on_message_added_callback, _tf_ssb_cleanup_value, ptr);
 		}
+		else if (strcmp(event_name, "blob") == 0)
+		{
+			void* ptr = JS_VALUE_GET_PTR(JS_DupValue(context, callback));
+			tf_ssb_add_blob_stored_callback(ssb, _tf_ssb_on_blob_stored_callback, _tf_ssb_cleanup_value, ptr);
+		}
 		else if (strcmp(event_name, "blob_want_added") == 0)
 		{
 			void* ptr = JS_VALUE_GET_PTR(JS_DupValue(context, callback));
@@ -1790,6 +1809,11 @@ static JSValue _tf_ssb_remove_event_listener(JSContext* context, JSValueConst th
 			void* ptr = JS_VALUE_GET_PTR(JS_DupValue(context, callback));
 			tf_ssb_remove_message_added_callback(ssb, _tf_ssb_on_message_added_callback, ptr);
 		}
+		else if (strcmp(event_name, "blob") == 0)
+		{
+			void* ptr = JS_VALUE_GET_PTR(JS_DupValue(context, callback));
+			tf_ssb_remove_blob_stored_callback(ssb, _tf_ssb_on_blob_stored_callback, ptr);
+		}
 		else if (strcmp(event_name, "blob_want_added") == 0)
 		{
 			void* ptr = JS_VALUE_GET_PTR(JS_DupValue(context, callback));

src/ssb.tests.c

@@ -152,6 +152,12 @@ static void _wait_stored(tf_ssb_t* ssb, bool* stored)
 	}
 }
 
+static void _blob_stored(tf_ssb_t* ssb, const char* id, void* user_data)
+{
+	tf_printf("blob stored %s\n", id);
+	*(bool*)user_data = true;
+}
+
 void tf_ssb_test_ssb(const tf_test_options_t* options)
 {
 	tf_printf("Testing SSB.\n");
@@ -224,8 +230,13 @@ void tf_ssb_test_ssb(const tf_test_options_t* options)
 
 	char blob_id[k_id_base64_len] = { 0 };
 	const char* k_blob = "Hello, blob!";
+	bool blob_stored = false;
+	tf_ssb_add_blob_stored_callback(ssb0, _blob_stored, NULL, &blob_stored);
 	b = tf_ssb_db_blob_store(ssb0, (const uint8_t*)k_blob, strlen(k_blob), blob_id, sizeof(blob_id), NULL);
+	tf_ssb_notify_blob_stored(ssb0, blob_id);
+	tf_ssb_remove_blob_stored_callback(ssb0, _blob_stored, &blob_stored);
 	assert(b);
+	assert(blob_stored);
 
 	JSContext* context0 = tf_ssb_get_context(ssb0);
 	JSValue obj = JS_NewObject(context0);