ssb: Tweak idle scheduling even more, still. Fixes -t=bench.

src/ssb.c

@@ -17,6 +17,7 @@
 #include "sodium/crypto_scalarmult_curve25519.h"
 #include "sodium/crypto_secretbox.h"
 #include "sodium/crypto_sign.h"
+#include "sodium/randombytes.h"
 #include "sodium/utils.h"
 #include "sqlite3.h"
 #include "uv.h"
@@ -261,7 +262,7 @@ typedef struct _tf_ssb_connection_message_request_t
 
 typedef struct _tf_ssb_connection_scheduled_t
 {
-	char key[k_id_base64_len];
+	char key[128];
 	tf_ssb_scheduled_callback_t* callback;
 	void* user_data;
 } tf_ssb_connection_scheduled_t;
@@ -323,6 +324,7 @@ typedef struct _tf_ssb_connection_t
 	uint8_t secretbox_buf[k_tf_ssb_rpc_message_body_length_max];
 
 	uint32_t send_request_number;
+	uint64_t prng;
 
 	tf_ssb_connection_t* next;
 	tf_ssb_request_t* requests;
@@ -592,17 +594,26 @@ static void _tf_ssb_connection_scheduled_async(uv_async_t* async)
 	_tf_ssb_connection_dispatch_scheduled(connection);
 }
 
+static uint32_t _tf_ssb_connection_prng(tf_ssb_connection_t* connection)
+{
+	uint64_t seed = connection->prng * 6364136223846793005ULL + 1442695040888963407ULL;
+	uint32_t result = (uint32_t)((seed ^ (seed >> 22)) >> (22 + (seed >> 61)));
+	connection->prng = seed;
+	return result;
+}
+
 static void _tf_ssb_connection_dispatch_scheduled(tf_ssb_connection_t* connection)
 {
 	while (((connection->active_write_count == 0 && connection->read_back_pressure == 0) || connection->closing) && connection->scheduled_count && connection->scheduled)
 	{
-		int index = uv_hrtime() % connection->scheduled_count;
+		int index = _tf_ssb_connection_prng(connection) % connection->scheduled_count;
 		tf_ssb_connection_scheduled_t scheduled = connection->scheduled[index];
 		if (index != connection->scheduled_count - 1)
 		{
 			memmove(connection->scheduled + index, connection->scheduled + index + 1, sizeof(tf_ssb_connection_scheduled_t) * (connection->scheduled_count - index - 1));
 		}
 		connection->scheduled_count--;
+
 		tf_trace_begin(connection->ssb->trace, "scheduled callback");
 		PRE_CALLBACK(connection->ssb, scheduled.callback);
 		scheduled.callback(connection, false, scheduled.user_data);
@@ -623,14 +634,11 @@ void tf_ssb_connection_schedule_idle(tf_ssb_connection_t* connection, const char
 	int index = tf_util_insert_index(key, connection->scheduled, connection->scheduled_count, sizeof(tf_ssb_connection_scheduled_t), _tf_ssb_connection_scheduled_compare);
 	if (index != connection->scheduled_count && strcmp(key, connection->scheduled[index].key) == 0)
 	{
-		tf_ssb_connection_scheduled_t scheduled = connection->scheduled[index];
-		connection->scheduled[index].callback = callback;
-		connection->scheduled[index].user_data = user_data;
-
+		/* Keep the old request.  Skip the new request. */
 		tf_trace_begin(connection->ssb->trace, "scheduled callback (skip)");
-		PRE_CALLBACK(connection->ssb, scheduled.callback);
-		scheduled.callback(connection, true, scheduled.user_data);
-		POST_CALLBACK(connection->ssb, scheduled.callback);
+		PRE_CALLBACK(connection->ssb, callback);
+		callback(connection, true, user_data);
+		POST_CALLBACK(connection->ssb, callback);
 		tf_trace_end(connection->ssb->trace);
 	}
 	else
@@ -2728,6 +2736,7 @@ static tf_ssb_connection_t* _tf_ssb_connection_create_internal(tf_ssb_t* ssb, co
 	snprintf(connection->name, sizeof(connection->name), "%s%d", name, index);
 	connection->ssb = ssb;
 	connection->send_request_number = 1;
+	randombytes_buf(&connection->prng, sizeof(connection->prng));
 
 	connection->async.data = connection;
 	uv_async_init(ssb->loop, &connection->async, _tf_ssb_connection_process_message_async);

src/ssb.h

@@ -807,7 +807,7 @@ typedef void(tf_ssb_scheduled_callback_t)(tf_ssb_connection_t* connection, bool
 /**
 ** Schedule work to be run when the connection is next idle.
 ** @param connection The owning connection.
-** @param key A key identifying the work.  If work by the same key already exists, it will be replaced.
+** @param key A key identifying the work.  If work by the same key already exists, the new request will be discarded.
 ** @param callback The callback to call.
 ** @param user_data User data to pass to the callback.
 */

src/ssb.rpc.c

@@ -908,7 +908,7 @@ static void _tf_ssb_connection_send_history_stream_callback(tf_ssb_connection_t*
 static void _tf_ssb_connection_send_history_stream(
 	tf_ssb_connection_t* connection, int32_t request_number, const char* author, int64_t sequence, bool keys, bool live, bool end_request)
 {
-	if (!tf_ssb_is_shutting_down(tf_ssb_connection_get_ssb(connection)))
+	if (tf_ssb_connection_is_connected(connection) && !tf_ssb_is_shutting_down(tf_ssb_connection_get_ssb(connection)))
 	{
 		tf_ssb_connection_send_history_stream_t* async = tf_malloc(sizeof(tf_ssb_connection_send_history_stream_t));
 		*async = (tf_ssb_connection_send_history_stream_t) {
@@ -919,7 +919,9 @@ static void _tf_ssb_connection_send_history_stream(
 			.end_request = end_request,
 		};
 		snprintf(async->author, sizeof(async->author), "%s", author);
-		tf_ssb_connection_schedule_idle(connection, author, _tf_ssb_connection_send_history_stream_callback, async);
+		char key[128];
+		snprintf(key, sizeof(key), "%s:%" PRId64, author, sequence);
+		tf_ssb_connection_schedule_idle(connection, key, _tf_ssb_connection_send_history_stream_callback, async);
 	}
 }