Port RPC interface introduced.

Usage:
1. Register handlers in incoming port with nxt_port_rpc_register_handler().
2. Use return value as a stream identifier for next nxt_port_socket_write().

9 files changed, 369 insertions, 0 deletions

diff --git a/auto/sources b/auto/sources
index 04cc6297..f4447c2a 100644
--- a/auto/sources
+++ b/auto/sources
@@ -90,6 +90,7 @@ NXT_LIB_SRCS=" \
     src/nxt_signal.c \
     src/nxt_port_socket.c \
     src/nxt_port_memory.c \
+    src/nxt_port_rpc.c \
     src/nxt_port.c \
     src/nxt_dyld.c \
     src/nxt_random.c \
diff --git a/src/nxt_main.h b/src/nxt_main.h
index 547a0321..72b243f4 100644
--- a/src/nxt_main.h
+++ b/src/nxt_main.h
@@ -126,6 +126,7 @@ nxt_thread_extern_data(nxt_thread_t, nxt_thread_context);
 
 #include <nxt_port.h>
 #include <nxt_port_memory.h>
+#include <nxt_port_rpc.h>
 #if (NXT_THREADS)
 #include <nxt_thread_pool.h>
 #endif
diff --git a/src/nxt_master_process.c b/src/nxt_master_process.c
index bd72a752..9e32785f 100644
--- a/src/nxt_master_process.c
+++ b/src/nxt_master_process.c
@@ -200,6 +200,8 @@ static nxt_port_handler_t  nxt_master_process_port_handlers[] = {
     nxt_port_master_data_handler,
     NULL,
     nxt_port_ready_handler,
+    nxt_port_rpc_handler,
+    nxt_port_rpc_handler,
 };
 
 
diff --git a/src/nxt_port.c b/src/nxt_port.c
index 3c6b60b7..27b5ddbe 100644
--- a/src/nxt_port.c
+++ b/src/nxt_port.c
@@ -34,6 +34,7 @@ nxt_port_new(nxt_port_id_t id, nxt_pid_t pid, nxt_process_type_t type)
         port->pid = pid;
         port->type = type;
         port->mem_pool = mp;
+        port->next_stream = 1;
 
         nxt_queue_init(&port->messages);
 
@@ -421,6 +422,8 @@ nxt_port_remove_pid_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
     rt = task->thread->runtime;
     pid = msg->port_msg.stream;
 
+    nxt_port_rpc_remove_peer(task, msg->port, pid);
+
     process = nxt_runtime_process_find(rt, pid);
 
     if (process) {
diff --git a/src/nxt_port.h b/src/nxt_port.h
index 27c00132..1cbaaef1 100644
--- a/src/nxt_port.h
+++ b/src/nxt_port.h
@@ -21,6 +21,8 @@ typedef enum {
     _NXT_PORT_MSG_DATA,
     _NXT_PORT_MSG_REMOVE_PID,
     _NXT_PORT_MSG_READY,
+    _NXT_PORT_MSG_RPC_READY,
+    _NXT_PORT_MSG_RPC_ERROR,
 
     NXT_PORT_MSG_MAX,
 
@@ -33,6 +35,9 @@ typedef enum {
     NXT_PORT_MSG_DATA_LAST      = _NXT_PORT_MSG_DATA | NXT_PORT_MSG_LAST,
     NXT_PORT_MSG_REMOVE_PID     = _NXT_PORT_MSG_REMOVE_PID | NXT_PORT_MSG_LAST,
     NXT_PORT_MSG_READY          = _NXT_PORT_MSG_READY | NXT_PORT_MSG_LAST,
+    NXT_PORT_MSG_RPC_READY      = _NXT_PORT_MSG_RPC_READY,
+    NXT_PORT_MSG_RPC_READY_LAST = _NXT_PORT_MSG_RPC_READY | NXT_PORT_MSG_LAST,
+    NXT_PORT_MSG_RPC_ERROR      = _NXT_PORT_MSG_RPC_ERROR | NXT_PORT_MSG_LAST,
 } nxt_port_msg_type_t;
 
 
@@ -104,6 +109,10 @@ struct nxt_port_s {
     nxt_port_id_t       id;
     nxt_pid_t           pid;
 
+    nxt_lvlhsh_t        rpc_streams; /* stream to nxt_port_rpc_reg_t */
+    nxt_lvlhsh_t        rpc_peers;   /* peer to queue of nxt_port_rpc_reg_t */
+    uint32_t            next_stream;
+
     nxt_process_type_t  type;
     nxt_work_t          work;
 };
diff --git a/src/nxt_port_rpc.c b/src/nxt_port_rpc.c
new file mode 100644
index 00000000..e6126748
--- /dev/null
+++ b/src/nxt_port_rpc.c
@@ -0,0 +1,314 @@
+
+/*
+ * Copyright (C) Max Romanov
+ * Copyright (C) NGINX, Inc.
+ */
+
+#include <nxt_main.h>
+#include <nxt_port_rpc.h>
+
+
+typedef struct nxt_port_rpc_reg_s nxt_port_rpc_reg_t;
+
+struct nxt_port_rpc_reg_s {
+    uint32_t                stream;
+
+    nxt_pid_t               peer;
+    nxt_queue_link_t        link;
+
+    nxt_port_rpc_handler_t  ready_handler;
+    nxt_port_rpc_handler_t  error_handler;
+    void                    *data;
+};
+
+
+static nxt_int_t
+nxt_rpc_reg_test(nxt_lvlhsh_query_t *lhq, void *data)
+{
+    return NXT_OK;
+}
+
+
+static const nxt_lvlhsh_proto_t  lvlhsh_rpc_reg_proto  nxt_aligned(64) = {
+    NXT_LVLHSH_DEFAULT,
+    nxt_rpc_reg_test,
+    nxt_lvlhsh_alloc,
+    nxt_lvlhsh_free,
+};
+
+
+nxt_inline void
+nxt_port_rpc_lhq_stream(nxt_lvlhsh_query_t *lhq, uint32_t *stream)
+{
+    lhq->key_hash = nxt_murmur_hash2(stream, sizeof(*stream));
+    lhq->key.length = sizeof(*stream);
+    lhq->key.start = (u_char *) stream;
+    lhq->proto = &lvlhsh_rpc_reg_proto;
+}
+
+
+nxt_inline void
+nxt_port_rpc_lhq_peer(nxt_lvlhsh_query_t *lhq, nxt_pid_t *peer)
+{
+    lhq->key_hash = nxt_murmur_hash2(peer, sizeof(*peer));
+    lhq->key.length = sizeof(*peer);
+    lhq->key.start = (u_char *) peer;
+    lhq->proto = &lvlhsh_rpc_reg_proto;
+}
+
+
+uint32_t
+nxt_port_rpc_register_handler(nxt_task_t *task, nxt_port_t *port,
+    nxt_port_rpc_handler_t ready_handler, nxt_port_rpc_handler_t error_handler,
+    nxt_pid_t peer, void *data)
+{
+    uint32_t            stream;
+    nxt_queue_link_t    *peer_link;
+    nxt_port_rpc_reg_t  *reg;
+    nxt_lvlhsh_query_t  lhq;
+
+
+    nxt_assert(port->pair[0] != -1);  
+
+    stream = port->next_stream++;
+
+    reg = nxt_mp_zalloc(port->mem_pool, sizeof(nxt_port_rpc_reg_t));
+
+    if (nxt_slow_path(reg == NULL)) {
+        nxt_log_error(NXT_LOG_ERR, task->log, "rpc: failed to allocate "
+                      "reg for stream #%uD", stream);
+
+        return 0;
+    }
+
+    reg->stream = stream;
+    reg->peer = peer;
+    reg->ready_handler = ready_handler;
+    reg->error_handler = error_handler;
+    reg->data = data;
+
+
+    nxt_port_rpc_lhq_stream(&lhq, &stream);
+    lhq.replace = 0;
+    lhq.value = reg;
+    lhq.pool = port->mem_pool;
+
+    switch (nxt_lvlhsh_insert(&port->rpc_streams, &lhq)) {
+
+    case NXT_OK:
+        break;
+
+    default:
+        nxt_log_error(NXT_LOG_ERR, task->log, "rpc: failed to add handler "
+                      "for stream #%uD", stream);
+
+        nxt_mp_free(port->mem_pool, reg);
+
+        return 0;
+    }
+
+
+    nxt_port_rpc_lhq_peer(&lhq, &peer);
+    lhq.replace = 0;
+    lhq.value = &reg->link;
+    lhq.pool = port->mem_pool;
+
+    switch (nxt_lvlhsh_insert(&port->rpc_peers, &lhq)) {
+
+    case NXT_OK:
+        nxt_queue_self(&reg->link);
+        break;
+
+    case NXT_DECLINED:
+        peer_link = lhq.value;
+        nxt_queue_insert_before(peer_link, &reg->link);
+        break;
+
+    default:
+        nxt_log_error(NXT_LOG_ERR, task->log, "rpc: failed to add peer "
+                      "for stream #%uD", stream);
+        break;
+    }
+
+    return stream;
+}
+
+
+void
+nxt_port_rpc_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
+{
+    uint8_t              last;
+    uint32_t             stream;
+    nxt_int_t            ret;
+    nxt_port_t           *port;
+    nxt_port_rpc_reg_t   *reg;
+    nxt_lvlhsh_query_t   lhq;
+    nxt_port_msg_type_t  type;
+
+    stream = msg->port_msg.stream;
+    port = msg->port;
+    last = msg->port_msg.last;
+    type = msg->port_msg.type;
+
+    nxt_debug(task, "rpc: handler for stream #%uD, type %d", stream, type);
+
+    nxt_port_rpc_lhq_stream(&lhq, &stream);
+    lhq.pool = port->mem_pool;
+
+    if (last != 0) {
+        ret = nxt_lvlhsh_delete(&port->rpc_streams, &lhq);
+    } else {
+        ret = nxt_lvlhsh_find(&port->rpc_streams, &lhq);
+    }
+
+    if (ret != NXT_OK) {
+        nxt_debug(task, "rpc: no handler found for stream #%uD", stream);
+
+        return;
+    }
+
+    reg = lhq.value;
+
+    nxt_assert(reg->peer == msg->port_msg.pid);
+
+    if (type == _NXT_PORT_MSG_RPC_ERROR) {
+        reg->error_handler(task, msg, reg->data);
+    } else {
+        reg->ready_handler(task, msg, reg->data);
+    }
+
+    if (last == 0) {
+        nxt_debug(task, "rpc: keep handler for stream #%uD", stream);
+
+        return;
+    }
+
+    if (reg->link.next == &reg->link) {
+        nxt_port_rpc_lhq_peer(&lhq, &reg->peer);
+        lhq.pool = port->mem_pool;
+
+        ret = nxt_lvlhsh_delete(&port->rpc_peers, &lhq);
+
+        if (nxt_slow_path(ret != NXT_OK)) {
+            nxt_log_error(NXT_LOG_ERR, task->log, "rpc: failed to delete "
+                          "peer %PI", reg->peer);
+        }
+    } else {
+        nxt_queue_remove(&reg->link);
+    }
+
+    nxt_mp_free(port->mem_pool, reg);
+}
+
+
+void
+nxt_port_rpc_remove_peer(nxt_task_t *task, nxt_port_t *port, nxt_pid_t peer)
+{
+    uint8_t              last;
+    uint32_t             stream;
+    nxt_int_t            ret;
+    nxt_buf_t            buf;
+    nxt_queue_link_t     *peer_link;
+    nxt_port_rpc_reg_t   *reg;
+    nxt_lvlhsh_query_t   lhq;
+    nxt_port_recv_msg_t  msg;
+
+    nxt_port_rpc_lhq_peer(&lhq, &peer);
+    lhq.pool = port->mem_pool;
+
+    ret = nxt_lvlhsh_delete(&port->rpc_peers, &lhq);
+
+    if (nxt_slow_path(ret != NXT_OK)) {
+        nxt_debug(task, "rpc: no handler found for peer %PI", peer);
+
+        return;
+    }
+
+    nxt_memzero(&msg, sizeof(msg));
+    nxt_memzero(&buf, sizeof(buf));
+
+    msg.fd = -1;
+    msg.buf = &buf;
+    msg.port = port;
+
+    msg.port_msg.pid = peer;
+    msg.port_msg.type = _NXT_PORT_MSG_REMOVE_PID;
+    msg.port_msg.last = 1;
+
+    peer_link = lhq.value;
+    last = 0;
+
+    while (last == 0) {
+
+        reg = nxt_queue_link_data(peer_link, nxt_port_rpc_reg_t, link);
+
+        nxt_debug(task, "rpc: trigger error for stream #%uD", reg->stream);
+
+        msg.port_msg.stream = reg->stream;
+
+        reg->error_handler(task, &msg, reg->data);
+
+
+        stream = reg->stream;
+
+        nxt_port_rpc_lhq_stream(&lhq, &stream);
+        lhq.pool = port->mem_pool;
+
+        ret = nxt_lvlhsh_delete(&port->rpc_streams, &lhq);
+
+        if (nxt_slow_path(ret != NXT_OK)) {
+            nxt_log_error(NXT_LOG_ERR, task->log, "rpc: failed to delete "
+                          "handler for stream #%uD", stream);
+
+            return;
+        }
+
+        if (peer_link == peer_link->next) {
+            last = 1;
+
+        } else {
+            peer_link = peer_link->next;
+            nxt_queue_remove(peer_link->prev);
+        }
+
+        nxt_mp_free(port->mem_pool, reg);
+    }
+}
+
+
+void
+nxt_port_rpc_cancel(nxt_task_t *task, nxt_port_t *port, uint32_t stream)
+{
+    nxt_int_t           ret;
+    nxt_port_rpc_reg_t  *reg;
+    nxt_lvlhsh_query_t  lhq;
+
+    nxt_port_rpc_lhq_stream(&lhq, &stream);
+    lhq.pool = port->mem_pool;
+
+    ret = nxt_lvlhsh_delete(&port->rpc_streams, &lhq);
+
+    if (ret != NXT_OK) {
+        nxt_debug(task, "rpc: no handler found for stream %uxD", stream);
+
+        return;
+    }
+
+    reg = lhq.value;
+
+    if (reg->link.next == &reg->link) {
+        nxt_port_rpc_lhq_peer(&lhq, &reg->peer);
+        lhq.pool = port->mem_pool;
+
+        ret = nxt_lvlhsh_delete(&port->rpc_peers, &lhq);
+
+        if (nxt_slow_path(ret != NXT_OK)) {
+            nxt_log_error(NXT_LOG_ERR, task->log, "rpc: failed to delete "
+                          "peer %PI", reg->peer);
+        }
+    } else {
+        nxt_queue_remove(&reg->link);
+    }
+
+    nxt_mp_free(port->mem_pool, reg);
+}
diff --git a/src/nxt_port_rpc.h b/src/nxt_port_rpc.h
new file mode 100644
index 00000000..cae20539
--- /dev/null
+++ b/src/nxt_port_rpc.h
@@ -0,0 +1,24 @@
+
+/*
+ * Copyright (C) Max Romanov
+ * Copyright (C) NGINX, Inc.
+ */
+
+#ifndef _NXT_PORT_RPC_H_INCLUDED_
+#define _NXT_PORT_RPC_H_INCLUDED_
+
+
+typedef void (*nxt_port_rpc_handler_t)(nxt_task_t *task,
+    nxt_port_recv_msg_t *msg, void *data);
+
+uint32_t nxt_port_rpc_register_handler(nxt_task_t *task, nxt_port_t *port,
+    nxt_port_rpc_handler_t ready_handler, nxt_port_rpc_handler_t error_handler,
+    nxt_pid_t peer, void *data);
+void nxt_port_rpc_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg);
+void nxt_port_rpc_remove_peer(nxt_task_t *task, nxt_port_t *port,
+    nxt_pid_t peer);
+void nxt_port_rpc_cancel(nxt_task_t *task, nxt_port_t *port, uint32_t stream);
+
+
+#endif /* _NXT_PORT_RPC_H_INCLUDED_ */
+
diff --git a/src/nxt_router.c b/src/nxt_router.c
index 64cc53b7..ecce72ac 100644
--- a/src/nxt_router.c
+++ b/src/nxt_router.c
@@ -1407,6 +1407,9 @@ static nxt_port_handler_t  nxt_router_app_port_handlers[] = {
     nxt_port_mmap_handler,
     nxt_router_app_data_handler,
     nxt_port_remove_pid_handler,
+    NULL,
+    nxt_port_rpc_handler,
+    nxt_port_rpc_handler,
 };
 
 
diff --git a/src/nxt_worker_process.c b/src/nxt_worker_process.c
index a7db8b6b..83c63445 100644
--- a/src/nxt_worker_process.c
+++ b/src/nxt_worker_process.c
@@ -29,6 +29,9 @@ nxt_port_handler_t  nxt_controller_process_port_handlers[] = {
     nxt_port_mmap_handler,
     nxt_port_controller_data_handler,
     nxt_port_remove_pid_handler,
+    NULL,
+    nxt_port_rpc_handler,
+    nxt_port_rpc_handler,
 };
 
 
@@ -39,6 +42,9 @@ nxt_port_handler_t  nxt_worker_process_port_handlers[] = {
     nxt_port_mmap_handler,
     nxt_port_data_handler,
     nxt_port_remove_pid_handler,
+    NULL,
+    nxt_port_rpc_handler,
+    nxt_port_rpc_handler,
 };
 
 
@@ -49,6 +55,9 @@ nxt_port_handler_t  nxt_app_process_port_handlers[] = {
     nxt_port_mmap_handler,
     nxt_port_app_data_handler,
     nxt_port_remove_pid_handler,
+    NULL,
+    nxt_port_rpc_handler,
+    nxt_port_rpc_handler,
 };
 
 
@@ -59,6 +68,9 @@ nxt_port_handler_t  nxt_router_process_port_handlers[] = {
     nxt_port_mmap_handler,
     nxt_router_conf_data_handler,
     nxt_port_remove_pid_handler,
+    NULL,
+    nxt_port_rpc_handler,
+    nxt_port_rpc_handler,
 };