Rebase based on unstable branch

---------

Signed-off-by: Lipeng Zhu <[email protected]>
Co-authored-by: Wangyang Guo <[email protected]>

src/Makefile

@@ -318,6 +318,17 @@ else
 	LIBCRYPTO_LIBS=-lcrypto
 endif
 
+# only Linux has IO_URING support
+ifeq ($(uname_S),Linux)
+HAS_LIBURING := $(shell sh -c 'echo "$(NUMBER_SIGN_CHAR)include <liburing.h>" > foo.c; \
+	$(CC) -E foo.c > /dev/null 2>&1 && echo yes; \
+	rm foo.c')
+ifeq ($(HAS_LIBURING),yes)
+	FINAL_CFLAGS+= -DHAVE_LIBURING
+	FINAL_LIBS+= -luring
+endif
+endif
+
 BUILD_NO:=0
 BUILD_YES:=1
 BUILD_MODULE:=2
@@ -401,7 +412,7 @@ endif
 ENGINE_NAME=valkey
 SERVER_NAME=$(ENGINE_NAME)-server$(PROG_SUFFIX)
 ENGINE_SENTINEL_NAME=$(ENGINE_NAME)-sentinel$(PROG_SUFFIX)
-ENGINE_SERVER_OBJ=threads_mngr.o adlist.o quicklist.o ae.o anet.o dict.o kvstore.o server.o sds.o zmalloc.o lzf_c.o lzf_d.o pqsort.o zipmap.o sha1.o ziplist.o release.o io_threads.o networking.o util.o object.o db.o replication.o rdb.o t_string.o t_list.o t_set.o t_zset.o t_hash.o config.o aof.o pubsub.o multi.o debug.o sort.o intset.o syncio.o cluster.o cluster_legacy.o cluster_slot_stats.o crc16.o endianconv.o slowlog.o eval.o bio.o rio.o rand.o memtest.o syscheck.o crcspeed.o crccombine.o crc64.o bitops.o sentinel.o notify.o setproctitle.o blocked.o hyperloglog.o latency.o sparkline.o valkey-check-rdb.o valkey-check-aof.o geo.o lazyfree.o module.o evict.o expire.o geohash.o geohash_helper.o childinfo.o defrag.o siphash.o rax.o t_stream.o listpack.o localtime.o lolwut.o lolwut5.o lolwut6.o acl.o tracking.o socket.o tls.o sha256.o timeout.o setcpuaffinity.o monotonic.o mt19937-64.o resp_parser.o call_reply.o script_lua.o script.o functions.o function_lua.o commands.o strl.o connection.o unix.o logreqres.o
+ENGINE_SERVER_OBJ=threads_mngr.o adlist.o quicklist.o ae.o anet.o dict.o kvstore.o server.o sds.o zmalloc.o lzf_c.o lzf_d.o pqsort.o zipmap.o sha1.o ziplist.o release.o io_threads.o networking.o util.o object.o db.o replication.o rdb.o t_string.o t_list.o t_set.o t_zset.o t_hash.o config.o aof.o pubsub.o multi.o debug.o sort.o intset.o syncio.o cluster.o cluster_legacy.o cluster_slot_stats.o crc16.o endianconv.o slowlog.o eval.o bio.o rio.o rand.o memtest.o syscheck.o crcspeed.o crccombine.o crc64.o bitops.o sentinel.o notify.o setproctitle.o blocked.o hyperloglog.o latency.o sparkline.o valkey-check-rdb.o valkey-check-aof.o geo.o lazyfree.o module.o evict.o expire.o geohash.o geohash_helper.o childinfo.o defrag.o siphash.o rax.o t_stream.o listpack.o localtime.o lolwut.o lolwut5.o lolwut6.o acl.o tracking.o socket.o tls.o sha256.o timeout.o setcpuaffinity.o monotonic.o mt19937-64.o resp_parser.o call_reply.o script_lua.o script.o functions.o function_lua.o commands.o strl.o connection.o unix.o logreqres.o io_uring.o
 ENGINE_CLI_NAME=$(ENGINE_NAME)-cli$(PROG_SUFFIX)
 ENGINE_CLI_OBJ=anet.o adlist.o dict.o valkey-cli.o zmalloc.o release.o ae.o serverassert.o crcspeed.o crccombine.o crc64.o siphash.o crc16.o monotonic.o cli_common.o mt19937-64.o strl.o cli_commands.o
 ENGINE_BENCHMARK_NAME=$(ENGINE_NAME)-benchmark$(PROG_SUFFIX)

src/config.c

@@ -3073,6 +3073,7 @@ standardConfig static_configs[] = {
     createBoolConfig("replica-ignore-disk-write-errors", NULL, MODIFIABLE_CONFIG, server.repl_ignore_disk_write_error, 0, NULL, NULL),
     createBoolConfig("extended-redis-compatibility", NULL, MODIFIABLE_CONFIG, server.extended_redis_compat, 0, NULL, updateExtendedRedisCompat),
     createBoolConfig("enable-debug-assert", NULL, IMMUTABLE_CONFIG | HIDDEN_CONFIG, server.enable_debug_assert, 0, NULL, NULL),
+    createBoolConfig("io-uring-enabled", NULL, IMMUTABLE_CONFIG, server.io_uring_enabled, 0, NULL, NULL),
 
     /* String Configs */
     createStringConfig("aclfile", NULL, IMMUTABLE_CONFIG, ALLOW_EMPTY_STRING, server.acl_filename, "", NULL, NULL),

src/io_uring.c

@@ -0,0 +1,140 @@
+#include "io_uring.h"
+
+#include <liburing.h>
+
+/* io_uring instance queue depth. */
+#define IO_URING_DEPTH 256
+
+static size_t io_uring_queue_len = 0;
+
+void initIOUring(void) {
+    if (server.io_uring_enabled) {
+        struct io_uring_params params;
+        struct io_uring *ring = zmalloc(sizeof(struct io_uring));
+        memset(&params, 0, sizeof(params));
+        /* On success, io_uring_queue_init_params(3) returns 0 and ring will
+         * point to the shared memory containing the io_uring queues.
+         * On failure -errno is returned. */
+        int ret = io_uring_queue_init_params(IO_URING_DEPTH, ring, &params);
+        if (ret != 0) {
+            /* Warning if user enable the io_uring in config but system doesn't support yet. */
+            serverLog(LL_WARNING, "System doesn't support io_uring, disable io_uring.");
+            zfree(ring);
+            server.io_uring = NULL;
+        } else {
+            serverLog(LL_NOTICE, "System support io_uring, enable io_uring.");
+            server.io_uring = ring;
+        }
+    }
+}
+
+int canWriteUsingIOUring(client *c) {
+    if (server.io_uring_enabled && server.io_uring) {
+        /* Currently, we only use io_uring to handle the static buffer write requests. */
+        return getClientType(c) != CLIENT_TYPE_REPLICA && listLength(c->reply) == 0 && c->bufpos > 0;
+    }
+    return 0;
+}
+
+int writeToClientUsingIOUring(client *c) {
+    c->flag.pending_io_uring_write = 1;
+    struct io_uring_sqe *sqe = io_uring_get_sqe(server.io_uring);
+    if (sqe == NULL) return C_ERR;
+    io_uring_prep_send(sqe, c->conn->fd, c->buf + c->sentlen, c->bufpos - c->sentlen, MSG_DONTWAIT);
+    io_uring_sqe_set_data(sqe, c);
+    io_uring_queue_len++;
+    return C_OK;
+}
+
+/* Submit requests to the submission queue and wait for completion. */
+static inline void ioUringSubmitAndWaitBarrier(void) {
+    io_uring_submit(server.io_uring);
+    /* Wait for all submitted queue entries complete. */
+    while (io_uring_queue_len) {
+        struct io_uring_cqe *cqe;
+        if (io_uring_wait_cqe(server.io_uring, &cqe) == 0) {
+            client *c = io_uring_cqe_get_data(cqe);
+            c->nwritten = cqe->res;
+            io_uring_cqe_seen(server.io_uring, cqe);
+            io_uring_queue_len--;
+        } else {
+            serverPanic("Error waiting io_uring completion queue.");
+        }
+    }
+}
+
+/* Check the completed io_uring event and update the state. */
+int checkPendingIOUringWriteState(client *c) {
+    /* Note that where synchronous system calls will return -1 on
+     * failure and set errno to the actual error value,
+     * io_uring never uses errno. Instead it returns the negated
+     * errno directly in the CQE res field. */
+    if (c->nwritten <= 0) {
+        if (c->nwritten != -EAGAIN) {
+            c->conn->last_errno = -(c->nwritten);
+            /* Don't overwrite the state of a connection that is not already
+             * connected, not to mess with handler callbacks. */
+            if (c->nwritten != -EINTR && c->conn->state == CONN_STATE_CONNECTED) c->conn->state = CONN_STATE_ERROR;
+        }
+        if (connGetState(c->conn) != CONN_STATE_CONNECTED) {
+            serverLog(LL_VERBOSE, "Error writing to client: %s", connGetLastError(c->conn));
+            freeClientAsync(c);
+        }
+        return C_ERR;
+    }
+
+    c->sentlen += c->nwritten;
+    /* If the buffer was sent, set bufpos to zero to continue with
+     * the remainder of the reply. */
+    if ((int)c->sentlen == c->bufpos) {
+        c->bufpos = 0;
+        c->sentlen = 0;
+    }
+    atomic_fetch_add_explicit(&server.stat_net_output_bytes, c->nwritten, memory_order_relaxed);
+    c->net_output_bytes += c->nwritten;
+
+    /* For clients representing masters we don't count sending data
+     * as an interaction, since we always send REPLCONF ACK commands
+     * that take some time to just fill the socket output buffer.
+     * We just rely on data / pings received for timeout detection. */
+    if (!c->flag.primary) c->last_interaction = server.unixtime;
+
+    return C_OK;
+}
+
+void submitAndWaitIOUringComplete() {
+    if (server.io_uring_enabled && server.io_uring && listLength(server.clients_pending_write) > 0) {
+        ioUringSubmitAndWaitBarrier();
+        listIter li;
+        listNode *ln;
+        /* An optimization for connWrite: batch submit the write(3). */
+        listRewind(server.clients_pending_write, &li);
+        while ((ln = listNext(&li))) {
+            client *c = listNodeValue(ln);
+            c->flag.pending_io_uring_write = 0;
+            listUnlinkNode(server.clients_pending_write, ln);
+
+            if (checkPendingIOUringWriteState(c) == C_ERR) continue;
+            if (!clientHasPendingReplies(c)) {
+                c->sentlen = 0;
+                /* Close connection after entire reply has been sent. */
+                if (c->flag.close_after_reply) {
+                    freeClientAsync(c);
+                    continue;
+                }
+            }
+            /* Update client's memory usage after writing.
+             * Since this isn't thread safe we do this conditionally. In case of threaded writes this is done in
+             * handleClientsWithPendingWritesUsingThreads(). */
+            updateClientMemUsageAndBucket(c);
+        }
+    }
+}
+
+void freeIOUring(void) {
+    if (server.io_uring_enabled && server.io_uring) {
+        io_uring_queue_exit(server.io_uring);
+        zfree(server.io_uring);
+        server.io_uring = NULL;
+    }
+}

src/io_uring.h

@@ -0,0 +1,21 @@
+#ifndef IO_URING_H
+#define IO_URING_H
+
+#include "server.h"
+
+/* Initialize io_uring at server startup if have io_uring configured, setup io_uring submission and completion. */
+void initIOUring(void);
+
+/* If the client is suitable to use io_uring handle the write request. */
+int canWriteUsingIOUring(client *c);
+
+/* Use io_uring to handle the client request, it is always used together with canWriteUsingIOUring(). */
+int writeToClientUsingIOUring(client *c);
+
+/* Submit requests to the submission queue and wait for completion. */
+void submitAndWaitIOUringComplete(void);
+
+/* Free io_uring. */
+void freeIOUring(void);
+
+#endif /* IO_URING_H */

src/server.c

@@ -40,6 +40,7 @@
 #include "threads_mngr.h"
 #include "fmtargs.h"
 #include "io_threads.h"
+#include "io_uring.h"
 
 #include <time.h>
 #include <signal.h>
@@ -2810,6 +2811,7 @@ void initListeners(void) {
 void InitServerLast(void) {
     bioInit();
     initIOThreads();
+    initIOUring();
     set_jemalloc_bg_thread(server.jemalloc_bg_thread);
     server.initial_memory_usage = zmalloc_used_memory();
 }
@@ -6984,6 +6986,7 @@ int main(int argc, char **argv) {
 
     aeMain(server.el);
     aeDeleteEventLoop(server.el);
+    freeIOUring();
     return 0;
 }
 

src/server.h

@@ -1180,7 +1180,8 @@ typedef struct ClientFlags {
     uint64_t reprocessing_command : 1;     /* The client is re-processing the command. */
     uint64_t replication_done : 1;         /* Indicate that replication has been done on the client */
     uint64_t authenticated : 1;            /* Indicate a client has successfully authenticated */
-    uint64_t reserved : 9;                 /* Reserved for future use */
+    uint64_t pending_io_uring_write : 1;   /* Client has output to send using io_uring. */
+    uint64_t reserved : 8;                 /* Reserved for future use */
 } ClientFlags;
 
 typedef struct client {
@@ -2123,6 +2124,9 @@ struct valkeyServer {
     sds availability_zone; /* When run in a cloud environment we can configure the availability zone it is running in */
     /* Local environment */
     char *locale_collate;
+    /* io_uring */
+    int io_uring_enabled;   /* Enable io_uring */
+    struct io_uring *io_uring;
 };
 
 #define MAX_KEYS_BUFFER 256

tests/unit/introspection.tcl

@@ -558,6 +558,7 @@ start_server {tags {"introspection"}} {
             socket-mark-id
             req-res-logfile
             client-default-resp
+            io-uring-enabled
         }
 
         if {!$::tls} {

valkey.conf

@@ -2313,4 +2313,10 @@ jemalloc-bg-thread yes
 # this is only exposed via the info command for clients to use, but in the future we
 # we may also use this when making decisions for replication.
 #
-# availability-zone "zone-name"
+# availability-zone "zone-name"
+
+# If Valkey is compiled with io_uring support and liburing is installed in the
+# system, then io_uring can be enabled with this config. The io_uring kernel
+# interface was adopted in Linux kernel version 5.1.
+#
+# io-uring-enabled no