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kc_hxd_jp:
博主问个问题,这个篇幅下的python代码无法达到应有的作用, ...
zeroMQ初体验-14.命名机制 进阶 -
kobe1029:
Map<String, Object> args ...
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Sasoritattoo:
LZ,这都13年了,抽空把这篇文章的下文给表完了吧,这一口气喘 ...
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3GQQ2012:
引用前文已经说过,XREP其实用以平衡负载,所以这里由它对请求 ...
zeroMQ初体验-15.应答模式进阶(一)-数据的封装 -
iyuan:
ustclz 写道图片怎么显示不了了。。我这看是可以显示的。不 ...
zeroMQ初体验-1.简介及C/S模式
临时缓存
现实中,比如DNS服务器,可以算是一个典型案例。临时存储一个节点,如果节点小时,那么该存储也会随之灰飞,所以,"过期"也是一个靠谱的需求。
由于有新的需求提出,我们的key-value库也得做些相应的改动:
服务器:
可靠性
任何东东,一旦脱离的 可靠性,那么终将只是个玩具,虽然它也会带来无尽的麻烦。
之前的"主从模式"似乎不错,再稍微变动下,把“从”也当作客户端之一,接受、存储所有的更新,是不是有点靠谱的感觉。
主从的状态机制模型图:
机制为:客户端发现主服务器不返回了,那么就向从服务器请求,从服务器确认主服务器的确不行了,于是就上马充当服务器。主回归后,从再变为一个客户端。
客户端:
客户端api:
(未完待续)
现实中,比如DNS服务器,可以算是一个典型案例。临时存储一个节点,如果节点小时,那么该存储也会随之灰飞,所以,"过期"也是一个靠谱的需求。
由于有新的需求提出,我们的key-value库也得做些相应的改动:
/* ===================================================================== kvmsg - key-value message class for example applications --------------------------------------------------------------------- Copyright (c) 1991-2011 iMatix Corporation <www.imatix.com> Copyright other contributors as noted in the AUTHORS file. This file is part of the ZeroMQ Guide: http://zguide.zeromq.org This is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. ===================================================================== */ #include "kvmsg.h" #include <uuid/uuid.h> #include "zlist.h" // Keys are short strings #define KVMSG_KEY_MAX 255 // Message is formatted on wire as 4 frames: // frame 0: key (0MQ string) // frame 1: sequence (8 bytes, network order) // frame 2: uuid (blob, 16 bytes) // frame 3: properties (0MQ string) // frame 4: body (blob) #define FRAME_KEY 0 #define FRAME_SEQ 1 #define FRAME_UUID 2 #define FRAME_PROPS 3 #define FRAME_BODY 4 #define KVMSG_FRAMES 5 // Structure of our class struct _kvmsg { // Presence indicators for each frame int present [KVMSG_FRAMES]; // Corresponding 0MQ message frames, if any zmq_msg_t frame [KVMSG_FRAMES]; // Key, copied into safe C string char key [KVMSG_KEY_MAX + 1]; // List of properties, as name=value strings zlist_t *props; size_t props_size; }; // Serialize list of properties to a message frame static void s_encode_props (kvmsg_t *self) { zmq_msg_t *msg = &self->frame [FRAME_PROPS]; if (self->present [FRAME_PROPS]) zmq_msg_close (msg); zmq_msg_init_size (msg, self->props_size); char *prop = zlist_first (self->props); char *dest = (char *) zmq_msg_data (msg); while (prop) { strcpy (dest, prop); dest += strlen (prop); *dest++ = '\n'; prop = zlist_next (self->props); } self->present [FRAME_PROPS] = 1; } // Rebuild properties list from message frame static void s_decode_props (kvmsg_t *self) { zmq_msg_t *msg = &self->frame [FRAME_PROPS]; self->props_size = 0; while (zlist_size (self->props)) free (zlist_pop (self->props)); size_t remainder = zmq_msg_size (msg); char *prop = (char *) zmq_msg_data (msg); char *eoln = memchr (prop, '\n', remainder); while (eoln) { *eoln = 0; zlist_append (self->props, strdup (prop)); self->props_size += strlen (prop) + 1; remainder -= strlen (prop) + 1; prop = eoln + 1; eoln = memchr (prop, '\n', remainder); } } // --------------------------------------------------------------------- // Constructor, sets sequence as provided kvmsg_t * kvmsg_new (int64_t sequence) { kvmsg_t *self; self = (kvmsg_t *) zmalloc (sizeof (kvmsg_t)); self->props = zlist_new (); kvmsg_set_sequence (self, sequence); return self; } // --------------------------------------------------------------------- // Destructor // Free shim, compatible with zhash_free_fn void kvmsg_free (void *ptr) { if (ptr) { kvmsg_t *self = (kvmsg_t *) ptr; // Destroy message frames if any int frame_nbr; for (frame_nbr = 0; frame_nbr < KVMSG_FRAMES; frame_nbr++) if (self->present [frame_nbr]) zmq_msg_close (&self->frame [frame_nbr]); // Destroy property list while (zlist_size (self->props)) free (zlist_pop (self->props)); zlist_destroy (&self->props); // Free object itself free (self); } } void kvmsg_destroy (kvmsg_t **self_p) { assert (self_p); if (*self_p) { kvmsg_free (*self_p); *self_p = NULL; } } // --------------------------------------------------------------------- // Create duplicate of kvmsg kvmsg_t * kvmsg_dup (kvmsg_t *self) { kvmsg_t *kvmsg = kvmsg_new (0); int frame_nbr; for (frame_nbr = 0; frame_nbr < KVMSG_FRAMES; frame_nbr++) { if (self->present [frame_nbr]) { zmq_msg_t *src = &self->frame [frame_nbr]; zmq_msg_t *dst = &kvmsg->frame [frame_nbr]; zmq_msg_init_size (dst, zmq_msg_size (src)); memcpy (zmq_msg_data (dst), zmq_msg_data (src), zmq_msg_size (src)); kvmsg->present [frame_nbr] = 1; } } kvmsg->props = zlist_copy (self->props); return kvmsg; } // --------------------------------------------------------------------- // Reads key-value message from socket, returns new kvmsg instance. kvmsg_t * kvmsg_recv (void *socket) { assert (socket); kvmsg_t *self = kvmsg_new (0); // Read all frames off the wire, reject if bogus int frame_nbr; for (frame_nbr = 0; frame_nbr < KVMSG_FRAMES; frame_nbr++) { if (self->present [frame_nbr]) zmq_msg_close (&self->frame [frame_nbr]); zmq_msg_init (&self->frame [frame_nbr]); self->present [frame_nbr] = 1; if (zmq_recvmsg (socket, &self->frame [frame_nbr], 0) == -1) { kvmsg_destroy (&self); break; } // Verify multipart framing int rcvmore = (frame_nbr < KVMSG_FRAMES - 1)? 1: 0; if (zsockopt_rcvmore (socket) != rcvmore) { kvmsg_destroy (&self); break; } } if (self) s_decode_props (self); return self; } // --------------------------------------------------------------------- // Send key-value message to socket; any empty frames are sent as such. void kvmsg_send (kvmsg_t *self, void *socket) { assert (self); assert (socket); s_encode_props (self); int frame_nbr; for (frame_nbr = 0; frame_nbr < KVMSG_FRAMES; frame_nbr++) { zmq_msg_t copy; zmq_msg_init (©); if (self->present [frame_nbr]) zmq_msg_copy (©, &self->frame [frame_nbr]); zmq_sendmsg (socket, ©, (frame_nbr < KVMSG_FRAMES - 1)? ZMQ_SNDMORE: 0); zmq_msg_close (©); } } // --------------------------------------------------------------------- // Return key from last read message, if any, else NULL char * kvmsg_key (kvmsg_t *self) { assert (self); if (self->present [FRAME_KEY]) { if (!*self->key) { size_t size = zmq_msg_size (&self->frame [FRAME_KEY]); if (size > KVMSG_KEY_MAX) size = KVMSG_KEY_MAX; memcpy (self->key, zmq_msg_data (&self->frame [FRAME_KEY]), size); self->key [size] = 0; } return self->key; } else return NULL; } // --------------------------------------------------------------------- // Return sequence nbr from last read message, if any int64_t kvmsg_sequence (kvmsg_t *self) { assert (self); if (self->present [FRAME_SEQ]) { assert (zmq_msg_size (&self->frame [FRAME_SEQ]) == 8); byte *source = zmq_msg_data (&self->frame [FRAME_SEQ]); int64_t sequence = ((int64_t) (source [0]) << 56) + ((int64_t) (source [1]) << 48) + ((int64_t) (source [2]) << 40) + ((int64_t) (source [3]) << 32) + ((int64_t) (source [4]) << 24) + ((int64_t) (source [5]) << 16) + ((int64_t) (source [6]) << 8) + (int64_t) (source [7]); return sequence; } else return 0; } // --------------------------------------------------------------------- // Return UUID from last read message, if any, else NULL byte * kvmsg_uuid (kvmsg_t *self) { assert (self); if (self->present [FRAME_UUID] && zmq_msg_size (&self->frame [FRAME_UUID]) == sizeof (uuid_t)) return (byte *) zmq_msg_data (&self->frame [FRAME_UUID]); else return NULL; } // --------------------------------------------------------------------- // Return body from last read message, if any, else NULL byte * kvmsg_body (kvmsg_t *self) { assert (self); if (self->present [FRAME_BODY]) return (byte *) zmq_msg_data (&self->frame [FRAME_BODY]); else return NULL; } // --------------------------------------------------------------------- // Return body size from last read message, if any, else zero size_t kvmsg_size (kvmsg_t *self) { assert (self); if (self->present [FRAME_BODY]) return zmq_msg_size (&self->frame [FRAME_BODY]); else return 0; } // --------------------------------------------------------------------- // Set message key as provided void kvmsg_set_key (kvmsg_t *self, char *key) { assert (self); zmq_msg_t *msg = &self->frame [FRAME_KEY]; if (self->present [FRAME_KEY]) zmq_msg_close (msg); zmq_msg_init_size (msg, strlen (key)); memcpy (zmq_msg_data (msg), key, strlen (key)); self->present [FRAME_KEY] = 1; } // --------------------------------------------------------------------- // Set message sequence number void kvmsg_set_sequence (kvmsg_t *self, int64_t sequence) { assert (self); zmq_msg_t *msg = &self->frame [FRAME_SEQ]; if (self->present [FRAME_SEQ]) zmq_msg_close (msg); zmq_msg_init_size (msg, 8); byte *source = zmq_msg_data (msg); source [0] = (byte) ((sequence >> 56) & 255); source [1] = (byte) ((sequence >> 48) & 255); source [2] = (byte) ((sequence >> 40) & 255); source [3] = (byte) ((sequence >> 32) & 255); source [4] = (byte) ((sequence >> 24) & 255); source [5] = (byte) ((sequence >> 16) & 255); source [6] = (byte) ((sequence >> 8) & 255); source [7] = (byte) ((sequence) & 255); self->present [FRAME_SEQ] = 1; } // --------------------------------------------------------------------- // Set message UUID to generated value void kvmsg_set_uuid (kvmsg_t *self) { assert (self); zmq_msg_t *msg = &self->frame [FRAME_UUID]; uuid_t uuid; uuid_generate (uuid); if (self->present [FRAME_UUID]) zmq_msg_close (msg); zmq_msg_init_size (msg, sizeof (uuid)); memcpy (zmq_msg_data (msg), uuid, sizeof (uuid)); self->present [FRAME_UUID] = 1; } // --------------------------------------------------------------------- // Set message body void kvmsg_set_body (kvmsg_t *self, byte *body, size_t size) { assert (self); zmq_msg_t *msg = &self->frame [FRAME_BODY]; if (self->present [FRAME_BODY]) zmq_msg_close (msg); self->present [FRAME_BODY] = 1; zmq_msg_init_size (msg, size); memcpy (zmq_msg_data (msg), body, size); } // --------------------------------------------------------------------- // Set message key using printf format void kvmsg_fmt_key (kvmsg_t *self, char *format, …) { char value [KVMSG_KEY_MAX + 1]; va_list args; assert (self); va_start (args, format); vsnprintf (value, KVMSG_KEY_MAX, format, args); va_end (args); kvmsg_set_key (self, value); } // --------------------------------------------------------------------- // Set message body using printf format void kvmsg_fmt_body (kvmsg_t *self, char *format, …) { char value [255 + 1]; va_list args; assert (self); va_start (args, format); vsnprintf (value, 255, format, args); va_end (args); kvmsg_set_body (self, (byte *) value, strlen (value)); } // --------------------------------------------------------------------- // Get message property, if set, else "" char * kvmsg_get_prop (kvmsg_t *self, char *name) { assert (strchr (name, '=') == NULL); char *prop = zlist_first (self->props); size_t namelen = strlen (name); while (prop) { if (strlen (prop) > namelen && memcmp (prop, name, namelen) == 0 && prop [namelen] == '=') return prop + namelen + 1; prop = zlist_next (self->props); } return ""; } // --------------------------------------------------------------------- // Set message property // Names cannot contain '='. Max length of value is 255 chars. void kvmsg_set_prop (kvmsg_t *self, char *name, char *format, …) { assert (strchr (name, '=') == NULL); char value [255 + 1]; va_list args; assert (self); va_start (args, format); vsnprintf (value, 255, format, args); va_end (args); // Allocate name=value string char *prop = malloc (strlen (name) + strlen (value) + 2); // Remove existing property if any sprintf (prop, "%s=", name); char *existing = zlist_first (self->props); while (existing) { if (memcmp (prop, existing, strlen (prop)) == 0) { self->props_size -= strlen (existing) + 1; zlist_remove (self->props, existing); free (existing); break; } existing = zlist_next (self->props); } // Add new name=value property string strcat (prop, value); zlist_append (self->props, prop); self->props_size += strlen (prop) + 1; } // --------------------------------------------------------------------- // Store entire kvmsg into hash map, if key/value are set. // Nullifies kvmsg reference, and destroys automatically when no longer // needed. If value is empty, deletes any previous value from store. void kvmsg_store (kvmsg_t **self_p, zhash_t *hash) { assert (self_p); if (*self_p) { kvmsg_t *self = *self_p; assert (self); if (kvmsg_size (self)) { if (self->present [FRAME_KEY] && self->present [FRAME_BODY]) { zhash_update (hash, kvmsg_key (self), self); zhash_freefn (hash, kvmsg_key (self), kvmsg_free); } } else zhash_delete (hash, kvmsg_key (self)); *self_p = NULL; } } // --------------------------------------------------------------------- // Dump message to stderr, for debugging and tracing void kvmsg_dump (kvmsg_t *self) { if (self) { if (!self) { fprintf (stderr, "NULL"); return; } size_t size = kvmsg_size (self); byte *body = kvmsg_body (self); fprintf (stderr, "[seq:%" PRId64 "]", kvmsg_sequence (self)); fprintf (stderr, "[key:%s]", kvmsg_key (self)); fprintf (stderr, "[size:%zd] ", size); if (zlist_size (self->props)) { fprintf (stderr, "["); char *prop = zlist_first (self->props); while (prop) { fprintf (stderr, "%s;", prop); prop = zlist_next (self->props); } fprintf (stderr, "]"); } int char_nbr; for (char_nbr = 0; char_nbr < size; char_nbr++) fprintf (stderr, "%02X", body [char_nbr]); fprintf (stderr, "\n"); } else fprintf (stderr, "NULL message\n"); } // --------------------------------------------------------------------- // Runs self test of class int kvmsg_test (int verbose) { kvmsg_t *kvmsg; printf (" * kvmsg: "); // Prepare our context and sockets zctx_t *ctx = zctx_new (); void *output = zsocket_new (ctx, ZMQ_DEALER); int rc = zmq_bind (output, "ipc://kvmsg_selftest.ipc"); assert (rc == 0); void *input = zsocket_new (ctx, ZMQ_DEALER); rc = zmq_connect (input, "ipc://kvmsg_selftest.ipc"); assert (rc == 0); zhash_t *kvmap = zhash_new (); // Test send and receive of simple message kvmsg = kvmsg_new (1); kvmsg_set_key (kvmsg, "key"); kvmsg_set_uuid (kvmsg); kvmsg_set_body (kvmsg, (byte *) "body", 4); if (verbose) kvmsg_dump (kvmsg); kvmsg_send (kvmsg, output); kvmsg_store (&kvmsg, kvmap); kvmsg = kvmsg_recv (input); if (verbose) kvmsg_dump (kvmsg); assert (streq (kvmsg_key (kvmsg), "key")); kvmsg_store (&kvmsg, kvmap); // Test send and receive of message with properties kvmsg = kvmsg_new (2); kvmsg_set_prop (kvmsg, "prop1", "value1"); kvmsg_set_prop (kvmsg, "prop2", "value1"); kvmsg_set_prop (kvmsg, "prop2", "value2"); kvmsg_set_key (kvmsg, "key"); kvmsg_set_uuid (kvmsg); kvmsg_set_body (kvmsg, (byte *) "body", 4); assert (streq (kvmsg_get_prop (kvmsg, "prop2"), "value2")); if (verbose) kvmsg_dump (kvmsg); kvmsg_send (kvmsg, output); kvmsg_destroy (&kvmsg); kvmsg = kvmsg_recv (input); if (verbose) kvmsg_dump (kvmsg); assert (streq (kvmsg_key (kvmsg), "key")); assert (streq (kvmsg_get_prop (kvmsg, "prop2"), "value2")); kvmsg_destroy (&kvmsg); // Shutdown and destroy all objects zhash_destroy (&kvmap); zctx_destroy (&ctx); printf ("OK\n"); return 0; }
服务器:
// // Clone server Model Five // // Lets us build this source without creating a library #include "kvmsg.c" // zloop reactor handlers static int s_snapshots (zloop_t *loop, void *socket, void *args); static int s_collector (zloop_t *loop, void *socket, void *args); static int s_flush_ttl (zloop_t *loop, void *socket, void *args); // Our server is defined by these properties typedef struct { zctx_t *ctx; // Context wrapper zhash_t *kvmap; // Key-value store zloop_t *loop; // zloop reactor int port; // Main port we're working on int64_t sequence; // How many updates we're at void *snapshot; // Handle snapshot requests void *publisher; // Publish updates to clients void *collector; // Collect updates from clients } clonesrv_t; int main (void) { clonesrv_t *self = (clonesrv_t *) zmalloc (sizeof (clonesrv_t)); self->port = 5556; self->ctx = zctx_new (); self->kvmap = zhash_new (); self->loop = zloop_new (); zloop_set_verbose (self->loop, FALSE); // Set up our clone server sockets self->snapshot = zsocket_new (self->ctx, ZMQ_ROUTER); self->publisher = zsocket_new (self->ctx, ZMQ_PUB); self->collector = zsocket_new (self->ctx, ZMQ_PULL); zsocket_bind (self->snapshot, "tcp://*:%d", self->port); zsocket_bind (self->publisher, "tcp://*:%d", self->port + 1); zsocket_bind (self->collector, "tcp://*:%d", self->port + 2); // Register our handlers with reactor zloop_reader (self->loop, self->snapshot, s_snapshots, self); zloop_reader (self->loop, self->collector, s_collector, self); zloop_timer (self->loop, 1000, 0, s_flush_ttl, self); // Run reactor until process interrupted zloop_start (self->loop); zloop_destroy (&self->loop); zhash_destroy (&self->kvmap); zctx_destroy (&self->ctx); free (self); return 0; } // --------------------------------------------------------------------- // Send snapshots to clients who ask for them static int s_send_single (char *key, void *data, void *args); // Routing information for a key-value snapshot typedef struct { void *socket; // ROUTER socket to send to zframe_t *identity; // Identity of peer who requested state char *subtree; // Client subtree specification } kvroute_t; static int s_snapshots (zloop_t *loop, void *snapshot, void *args) { clonesrv_t *self = (clonesrv_t *) args; zframe_t *identity = zframe_recv (snapshot); if (identity) { // Request is in second frame of message char *request = zstr_recv (snapshot); char *subtree = NULL; if (streq (request, "ICANHAZ?")) { free (request); subtree = zstr_recv (snapshot); } else printf ("E: bad request, aborting\n"); if (subtree) { // Send state socket to client kvroute_t routing = { snapshot, identity, subtree }; zhash_foreach (self->kvmap, s_send_single, &routing); // Now send END message with sequence number zclock_log ("I: sending shapshot=%d", (int) self->sequence); zframe_send (&identity, snapshot, ZFRAME_MORE); kvmsg_t *kvmsg = kvmsg_new (self->sequence); kvmsg_set_key (kvmsg, "KTHXBAI"); kvmsg_set_body (kvmsg, (byte *) subtree, 0); kvmsg_send (kvmsg, snapshot); kvmsg_destroy (&kvmsg); free (subtree); } } return 0; } // Send one state snapshot key-value pair to a socket // Hash item data is our kvmsg object, ready to send static int s_send_single (char *key, void *data, void *args) { kvroute_t *kvroute = (kvroute_t *) args; kvmsg_t *kvmsg = (kvmsg_t *) data; if (strlen (kvroute->subtree) <= strlen (kvmsg_key (kvmsg)) && memcmp (kvroute->subtree, kvmsg_key (kvmsg), strlen (kvroute->subtree)) == 0) { // Send identity of recipient first zframe_send (&kvroute->identity, kvroute->socket, ZFRAME_MORE + ZFRAME_REUSE); kvmsg_send (kvmsg, kvroute->socket); } return 0; } // --------------------------------------------------------------------- // Collect updates from clients static int s_collector (zloop_t *loop, void *collector, void *args) { clonesrv_t *self = (clonesrv_t *) args; kvmsg_t *kvmsg = kvmsg_recv (collector); if (kvmsg) { kvmsg_set_sequence (kvmsg, ++self->sequence); kvmsg_send (kvmsg, self->publisher); int ttl = atoi (kvmsg_get_prop (kvmsg, "ttl")); if (ttl) kvmsg_set_prop (kvmsg, "ttl", "%" PRId64, zclock_time () + ttl * 1000); kvmsg_store (&kvmsg, self->kvmap); zclock_log ("I: publishing update=%d", (int) self->sequence); } return 0; } // --------------------------------------------------------------------- // Purge ephemeral values that have expired static int s_flush_single (char *key, void *data, void *args); static int s_flush_ttl (zloop_t *loop, void *unused, void *args) { clonesrv_t *self = (clonesrv_t *) args; zhash_foreach (self->kvmap, s_flush_single, args); return 0; } // If key-value pair has expired, delete it and publish the // fact to listening clients. static int s_flush_single (char *key, void *data, void *args) { clonesrv_t *self = (clonesrv_t *) args; kvmsg_t *kvmsg = (kvmsg_t *) data; int64_t ttl; sscanf (kvmsg_get_prop (kvmsg, "ttl"), "%" PRId64, &ttl); if (ttl && zclock_time () >= ttl) { kvmsg_set_sequence (kvmsg, ++self->sequence); kvmsg_set_body (kvmsg, (byte *) "", 0); kvmsg_send (kvmsg, self->publisher); kvmsg_store (&kvmsg, self->kvmap); zclock_log ("I: publishing delete=%d", (int) self->sequence); } return 0; }
可靠性
任何东东,一旦脱离的 可靠性,那么终将只是个玩具,虽然它也会带来无尽的麻烦。
之前的"主从模式"似乎不错,再稍微变动下,把“从”也当作客户端之一,接受、存储所有的更新,是不是有点靠谱的感觉。
主从的状态机制模型图:
机制为:客户端发现主服务器不返回了,那么就向从服务器请求,从服务器确认主服务器的确不行了,于是就上马充当服务器。主回归后,从再变为一个客户端。
客户端:
// // Clone client Model Six // // Lets us build this source without creating a library #include "clone.c" #define SUBTREE "/client/" int main (void) { // Create distributed hash instance clone_t *clone = clone_new (); // Specify configuration clone_subtree (clone, SUBTREE); clone_connect (clone, "tcp://localhost", "5556"); clone_connect (clone, "tcp://localhost", "5566"); // Set random tuples into the distributed hash while (!zctx_interrupted) { // Set random value, check it was stored char key [255]; char value [10]; sprintf (key, "%s%d", SUBTREE, randof (10000)); sprintf (value, "%d", randof (1000000)); clone_set (clone, key, value, randof (30)); sleep (1); } clone_destroy (&clone); return 0; }
客户端api:
/* ===================================================================== clone - client-side Clone Pattern class --------------------------------------------------------------------- Copyright (c) 1991-2011 iMatix Corporation <www.imatix.com> Copyright other contributors as noted in the AUTHORS file. This file is part of the ZeroMQ Guide: http://zguide.zeromq.org This is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. ===================================================================== */ #include "clone.h" // If no server replies within this time, abandon request #define GLOBAL_TIMEOUT 4000 // msecs // Server considered dead if silent for this long #define SERVER_TTL 5000 // msecs // Number of servers we will talk to #define SERVER_MAX 2 // ===================================================================== // Synchronous part, works in our application thread // --------------------------------------------------------------------- // Structure of our class struct _clone_t { zctx_t *ctx; // Our context wrapper void *pipe; // Pipe through to clone agent }; // This is the thread that handles our real clone class static void clone_agent (void *args, zctx_t *ctx, void *pipe); // --------------------------------------------------------------------- // Constructor clone_t * clone_new (void) { clone_t *self; self = (clone_t *) zmalloc (sizeof (clone_t)); self->ctx = zctx_new (); self->pipe = zthread_fork (self->ctx, clone_agent, NULL); return self; } // --------------------------------------------------------------------- // Destructor void clone_destroy (clone_t **self_p) { assert (self_p); if (*self_p) { clone_t *self = *self_p; zctx_destroy (&self->ctx); free (self); *self_p = NULL; } } // --------------------------------------------------------------------- // Specify subtree for snapshot and updates, do before connect // Sends [SUBTREE][subtree] to the agent void clone_subtree (clone_t *self, char *subtree) { assert (self); zmsg_t *msg = zmsg_new (); zmsg_addstr (msg, "SUBTREE"); zmsg_addstr (msg, subtree); zmsg_send (&msg, self->pipe); } // --------------------------------------------------------------------- // Connect to new server endpoint // Sends [CONNECT][endpoint][service] to the agent void clone_connect (clone_t *self, char *address, char *service) { assert (self); zmsg_t *msg = zmsg_new (); zmsg_addstr (msg, "CONNECT"); zmsg_addstr (msg, address); zmsg_addstr (msg, service); zmsg_send (&msg, self->pipe); } // --------------------------------------------------------------------- // Set new value in distributed hash table // Sends [SET][key][value][ttl] to the agent void clone_set (clone_t *self, char *key, char *value, int ttl) { char ttlstr [10]; sprintf (ttlstr, "%d", ttl); assert (self); zmsg_t *msg = zmsg_new (); zmsg_addstr (msg, "SET"); zmsg_addstr (msg, key); zmsg_addstr (msg, value); zmsg_addstr (msg, ttlstr); zmsg_send (&msg, self->pipe); } // --------------------------------------------------------------------- // Lookup value in distributed hash table // Sends [GET][key] to the agent and waits for a value response // If there is no clone available, will eventually return NULL. char * clone_get (clone_t *self, char *key) { assert (self); assert (key); zmsg_t *msg = zmsg_new (); zmsg_addstr (msg, "GET"); zmsg_addstr (msg, key); zmsg_send (&msg, self->pipe); zmsg_t *reply = zmsg_recv (self->pipe); if (reply) { char *value = zmsg_popstr (reply); zmsg_destroy (&reply); return value; } return NULL; } // ===================================================================== // Asynchronous part, works in the background // --------------------------------------------------------------------- // Simple class for one server we talk to typedef struct { char *address; // Server address int port; // Server port void *snapshot; // Snapshot socket void *subscriber; // Incoming updates uint64_t expiry; // When server expires uint requests; // How many snapshot requests made? } server_t; static server_t * server_new (zctx_t *ctx, char *address, int port, char *subtree) { server_t *self = (server_t *) zmalloc (sizeof (server_t)); zclock_log ("I: adding server %s:%d…", address, port); self->address = strdup (address); self->port = port; self->snapshot = zsocket_new (ctx, ZMQ_DEALER); zsocket_connect (self->snapshot, "%s:%d", address, port); self->subscriber = zsocket_new (ctx, ZMQ_SUB); zsocket_connect (self->subscriber, "%s:%d", address, port + 1); zsockopt_set_subscribe (self->subscriber, subtree); return self; } static void server_destroy (server_t **self_p) { assert (self_p); if (*self_p) { server_t *self = *self_p; free (self->address); free (self); *self_p = NULL; } } // --------------------------------------------------------------------- // Our agent class // States we can be in #define STATE_INITIAL 0 // Before asking server for state #define STATE_SYNCING 1 // Getting state from server #define STATE_ACTIVE 2 // Getting new updates from server typedef struct { zctx_t *ctx; // Context wrapper void *pipe; // Pipe back to application zhash_t *kvmap; // Actual key/value table char *subtree; // Subtree specification, if any server_t *server [SERVER_MAX]; uint nbr_servers; // 0 to SERVER_MAX uint state; // Current state uint cur_server; // If active, server 0 or 1 int64_t sequence; // Last kvmsg processed void *publisher; // Outgoing updates } agent_t; static agent_t * agent_new (zctx_t *ctx, void *pipe) { agent_t *self = (agent_t *) zmalloc (sizeof (agent_t)); self->ctx = ctx; self->pipe = pipe; self->kvmap = zhash_new (); self->subtree = strdup (""); self->state = STATE_INITIAL; self->publisher = zsocket_new (self->ctx, ZMQ_PUB); return self; } static void agent_destroy (agent_t **self_p) { assert (self_p); if (*self_p) { agent_t *self = *self_p; int server_nbr; for (server_nbr = 0; server_nbr < self->nbr_servers; server_nbr++) server_destroy (&self->server [server_nbr]); zhash_destroy (&self->kvmap); free (self->subtree); free (self); *self_p = NULL; } } // Returns -1 if thread was interrupted static int agent_control_message (agent_t *self) { zmsg_t *msg = zmsg_recv (self->pipe); char *command = zmsg_popstr (msg); if (command == NULL) return -1; if (streq (command, "SUBTREE")) { free (self->subtree); self->subtree = zmsg_popstr (msg); } else if (streq (command, "CONNECT")) { char *address = zmsg_popstr (msg); char *service = zmsg_popstr (msg); if (self->nbr_servers < SERVER_MAX) { self->server [self->nbr_servers++] = server_new ( self->ctx, address, atoi (service), self->subtree); // We broadcast updates to all known servers zsocket_connect (self->publisher, "%s:%d", address, atoi (service) + 2); } else zclock_log ("E: too many servers (max. %d)", SERVER_MAX); free (address); free (service); } else if (streq (command, "SET")) { char *key = zmsg_popstr (msg); char *value = zmsg_popstr (msg); char *ttl = zmsg_popstr (msg); zhash_update (self->kvmap, key, (byte *) value); zhash_freefn (self->kvmap, key, free); // Send key-value pair on to server kvmsg_t *kvmsg = kvmsg_new (0); kvmsg_set_key (kvmsg, key); kvmsg_set_uuid (kvmsg); kvmsg_fmt_body (kvmsg, "%s", value); kvmsg_set_prop (kvmsg, "ttl", ttl); kvmsg_send (kvmsg, self->publisher); kvmsg_destroy (&kvmsg); puts (key); free (ttl); free (key); // Value is owned by hash table } else if (streq (command, "GET")) { char *key = zmsg_popstr (msg); char *value = zhash_lookup (self->kvmap, key); if (value) zstr_send (self->pipe, value); else zstr_send (self->pipe, ""); free (key); free (value); } free (command); zmsg_destroy (&msg); return 0; } // --------------------------------------------------------------------- // Asynchronous agent manages server pool and handles request/reply // dialog when the application asks for it. static void clone_agent (void *args, zctx_t *ctx, void *pipe) { agent_t *self = agent_new (ctx, pipe); while (TRUE) { zmq_pollitem_t poll_set [] = { { pipe, 0, ZMQ_POLLIN, 0 }, { 0, 0, ZMQ_POLLIN, 0 } }; int poll_timer = -1; int poll_size = 2; server_t *server = self->server [self->cur_server]; switch (self->state) { case STATE_INITIAL: // In this state we ask the server for a snapshot, // if we have a server to talk to… if (self->nbr_servers > 0) { zclock_log ("I: waiting for server at %s:%d…", server->address, server->port); if (server->requests < 2) { zstr_sendm (server->snapshot, "ICANHAZ?"); zstr_send (server->snapshot, self->subtree); server->requests++; } server->expiry = zclock_time () + SERVER_TTL; self->state = STATE_SYNCING; poll_set [1].socket = server->snapshot; } else poll_size = 1; break; case STATE_SYNCING: // In this state we read from snapshot and we expect // the server to respond, else we fail over. poll_set [1].socket = server->snapshot; break; case STATE_ACTIVE: // In this state we read from subscriber and we expect // the server to give hugz, else we fail over. poll_set [1].socket = server->subscriber; break; } if (server) { poll_timer = (server->expiry - zclock_time ()) * ZMQ_POLL_MSEC; if (poll_timer < 0) poll_timer = 0; } // ------------------------------------------------------------ // Poll loop int rc = zmq_poll (poll_set, poll_size, poll_timer); if (rc == -1) break; // Context has been shut down if (poll_set [0].revents & ZMQ_POLLIN) { if (agent_control_message (self)) break; // Interrupted } else if (poll_set [1].revents & ZMQ_POLLIN) { kvmsg_t *kvmsg = kvmsg_recv (poll_set [1].socket); if (!kvmsg) break; // Interrupted // Anything from server resets its expiry time server->expiry = zclock_time () + SERVER_TTL; if (self->state == STATE_SYNCING) { // Store in snapshot until we're finished server->requests = 0; if (streq (kvmsg_key (kvmsg), "KTHXBAI")) { self->sequence = kvmsg_sequence (kvmsg); self->state = STATE_ACTIVE; zclock_log ("I: received from %s:%d snapshot=%d", server->address, server->port, (int) self->sequence); kvmsg_destroy (&kvmsg); } else kvmsg_store (&kvmsg, self->kvmap); } else if (self->state == STATE_ACTIVE) { // Discard out-of-sequence updates, incl. hugz if (kvmsg_sequence (kvmsg) > self->sequence) { self->sequence = kvmsg_sequence (kvmsg); kvmsg_store (&kvmsg, self->kvmap); zclock_log ("I: received from %s:%d update=%d", server->address, server->port, (int) self->sequence); } else kvmsg_destroy (&kvmsg); } } else { // Server has died, failover to next zclock_log ("I: server at %s:%d didn't give hugz", server->address, server->port); self->cur_server = (self->cur_server + 1) % self->nbr_servers; self->state = STATE_INITIAL; } } agent_destroy (&self); }
(未完待续)
发表评论
-
IM选型(初)
2016-08-23 19:12 1636主要参考文章: https://r ... -
关于python和rabbitmq的那点事儿
2011-10-19 14:15 7956rabbitmq是一个消息中间件,在之前的zmq介绍中有略带提 ... -
zeroMQ初体验-34.发布/订阅模式进阶-克隆模式-下,结言
2011-05-26 16:09 4162服务器: // // Clone server Mod ... -
zeroMQ初体验-32.发布/订阅模式进阶-克隆模式-上
2011-05-26 15:04 3648在发布/订阅模式中,特别是现实应用中,总会因为这样那样的问题导 ... -
zeroMQ初体验-31.发布/订阅模式进阶-黑盒的高速订阅者
2011-05-25 16:55 2751作为发布/订阅模式的一个常用场景,大数据量的组播是有必要的。虽 ... -
zeroMQ初体验-30.发布/订阅模式进阶-自裁的蜗牛订阅者
2011-05-25 16:24 4537在初次介绍发布/订阅模式的时候,就已经抖出了这个包袱:如果订阅 ... -
zeroMQ初体验-29.可靠性-自由模式
2011-05-24 17:02 5398好吧,本以为这可能是一个更靠谱的模式,谁知(其实是我一厢情愿了 ... -
zeroMQ初体验-28.可靠性-主从模式
2011-05-23 14:47 5512虽然"硬盘模式" ... -
zeroMQ初体验-27.可靠性-硬盘模式
2011-05-23 13:44 3791在之前的种种模式中, ... -
zeroMQ初体验-26.可靠性-管家模式
2011-05-12 19:05 5648上一节末尾有说到协议,zeromq自然做了充沛的封装,&quo ... -
zeroMQ初体验-26.可靠性-管家模式
2011-05-12 19:03 1上一节末尾有说到协议,zeromq自然做了充沛的封装,&quo ... -
zeroMQ初体验-25.可靠性-偏执的海盗模式
2011-05-05 19:05 3563虽然说“简单的海盗模 ... -
zeroMQ初体验-24.可靠性-简单的海盗模式
2011-05-05 16:41 3210相较于“懒惰的”做了 ... -
zeroMQ初体验-23.可靠性-懒惰的海盗模式
2011-05-05 16:15 5059相较于通常的阻塞模式,这里只是做了一点简单的动作来加强系统的可 ... -
zeroMQ初体验-22.可靠性-总览
2011-04-26 19:25 5929在开篇就从曾对zeromq的可靠性做过质疑,不过,作为一个雄心 ... -
rabbitmq 队列长度预设的曲线方案
2011-04-21 14:36 3376zeromq中倒是直接支持这个功能的。 类似于设定队列长度或 ... -
zeroMQ初体验-21.应答模式进阶(七)-云计算
2011-04-18 19:14 3529这里给出了一个最近很火的"云计算"案例。 ... -
zeroMQ初体验-20.应答模式进阶(六)-多对多路由模式
2011-04-18 17:22 3868某些时候,为了冗余的需要,可能会有这样的需求: impo ... -
zeroMQ初体验-19.应答模式进阶(五)-异步式应答
2011-04-15 15:23 4832恩,这应该算是比较实 ... -
zeroMQ初体验-18.应答模式进阶(四)-定制路由3
2011-04-02 15:39 5175从经典到超越经典。 首 ...
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