git.m6w6.name Git - awesomized/libmemcached/blob - example/memcached_light.c

   1 /* -*- Mode: C; tab-width: 2; c-basic-offset: 2; indent-tabs-mode: nil -*- */
   2 /**
   3  * What is a library without an example to show you how to use the library?
   4  * This example use both interfaces to implement a small memcached server.
   5  * Please note that this is an exemple on how to use the library, not
   6  * an implementation of a scalable memcached server. If you look closely
   7  * at the example it isn't even multithreaded ;-)
   8  *
   9  * With that in mind, let me give you some pointers into the source:
  10  *   storage.c/h       - Implements the item store for this server and not really
  11  *                       interesting for this example.
  12  *   interface_v0.c    - Shows an implementation of the memcached server by using
  13  *                       the "raw" access to the packets as they arrive
  14  *   interface_v1.c    - Shows an implementation of the memcached server by using
  15  *                       the more "logical" interface.
  16  *   memcached_light.c - This file sets up all of the sockets and run the main
  17  *                       message loop.
  18  */
  19
  20 #include <assert.h>
  21 #include <sys/types.h>
  22 #include <sys/socket.h>
  23 #include <netdb.h>
  24 #include <netinet/tcp.h>
  25 #include <stdio.h>
  26 #include <unistd.h>
  27 #include <fcntl.h>
  28 #include <errno.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <poll.h>
  32
  33 #include <libmemcached/protocol_handler.h>
  34 #include <libmemcached/byteorder.h>
  35 #include "storage.h"
  36
  37 extern struct memcached_binary_protocol_callback_st interface_v0_impl;
  38 extern struct memcached_binary_protocol_callback_st interface_v1_impl;
  39
  40 static int server_sockets[1024];
  41 static int num_server_sockets= 0;
  42 static void* socket_userdata_map[1024];
  43 static bool verbose= false;
  44
  45 /**
  46  * Create a socket and bind it to a specific port number
  47  * @param port the port number to bind to
  48  */
  49 static int server_socket(const char *port) {
  50   struct addrinfo *ai;
  51   struct addrinfo hints= { .ai_flags= AI_PASSIVE,
  52                            .ai_family= AF_UNSPEC,
  53                            .ai_socktype= SOCK_STREAM };
  54
  55   int error= getaddrinfo("127.0.0.1", port, &hints, &ai);
  56   if (error != 0)
  57   {
  58     if (error != EAI_SYSTEM)
  59       fprintf(stderr, "getaddrinfo(): %s\n", gai_strerror(error));
  60     else
  61       perror("getaddrinfo()");
  62
  63     return 1;
  64   }
  65
  66   struct linger ling= {0, 0};
  67
  68   for (struct addrinfo *next= ai; next; next= next->ai_next)
  69   {
  70     int sock= socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
  71     if (sock == -1)
  72     {
  73       perror("Failed to create socket");
  74       continue;
  75     }
  76
  77     int flags= fcntl(sock, F_GETFL, 0);
  78     if (flags == -1)
  79     {
  80       perror("Failed to get socket flags");
  81       close(sock);
  82       continue;
  83     }
  84
  85     if ((flags & O_NONBLOCK) != O_NONBLOCK)
  86       if (fcntl(sock, F_SETFL, flags | O_NONBLOCK) == -1)
  87       {
  88         perror("Failed to set socket to nonblocking mode");
  89         close(sock);
  90         continue;
  91       }
  92
  93     flags= 1;
  94     if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&flags, sizeof(flags)) != 0)
  95       perror("Failed to set SO_REUSEADDR");
  96
  97     if (setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&flags, sizeof(flags)) != 0)
  98       perror("Failed to set SO_KEEPALIVE");
  99
 100     if (setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&ling, sizeof(ling)) != 0)
 101       perror("Failed to set SO_LINGER");
 102
 103     if (setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (void *)&flags, sizeof(flags)) != 0)
 104       perror("Failed to set TCP_NODELAY");
 105
 106     if (bind(sock, next->ai_addr, next->ai_addrlen) == -1)
 107     {
 108       if (errno != EADDRINUSE)
 109       {
 110         perror("bind()");
 111         freeaddrinfo(ai);
 112       }
 113       close(sock);
 114       continue;
 115     }
 116
 117     if (listen(sock, 1024) == -1)
 118     {
 119       perror("listen()");
 120       close(sock);
 121       continue;
 122     }
 123
 124     server_sockets[num_server_sockets++]= sock;
 125   }
 126
 127   freeaddrinfo(ai);
 128
 129   return (num_server_sockets > 0) ? 0 : 1;
 130 }
 131
 132 /**
 133  * Convert a command code to a textual string
 134  * @param cmd the comcode to convert
 135  * @return a textual string with the command or NULL for unknown commands
 136  */
 137 static const char* comcode2str(uint8_t cmd)
 138 {
 139   static const char * const text[] = {
 140     "GET", "SET", "ADD", "REPLACE", "DELETE",
 141     "INCREMENT", "DECREMENT", "QUIT", "FLUSH",
 142     "GETQ", "NOOP", "VERSION", "GETK", "GETKQ",
 143     "APPEND", "PREPEND", "STAT", "SETQ", "ADDQ",
 144     "REPLACEQ", "DELETEQ", "INCREMENTQ", "DECREMENTQ",
 145     "QUITQ", "FLUSHQ", "APPENDQ", "PREPENDQ"
 146   };
 147
 148   if (cmd <= PROTOCOL_BINARY_CMD_PREPENDQ)
 149     return text[cmd];
 150
 151   return NULL;
 152 }
 153
 154 /**
 155  * Print out the command we are about to execute
 156  */
 157 static void pre_execute(const void *cookie __attribute__((unused)),
 158                         protocol_binary_request_header *header __attribute__((unused)))
 159 {
 160   if (verbose)
 161   {
 162     const char *cmd= comcode2str(header->request.opcode);
 163     if (cmd != NULL)
 164       fprintf(stderr, "pre_execute from %p: %s\n", cookie, cmd);
 165     else
 166       fprintf(stderr, "pre_execute from %p: 0x%02x\n", cookie, header->request.opcode);
 167   }
 168 }
 169
 170 /**
 171  * Print out the command we just executed
 172  */
 173 static void post_execute(const void *cookie __attribute__((unused)),
 174                          protocol_binary_request_header *header __attribute__((unused)))
 175 {
 176   if (verbose)
 177   {
 178     const char *cmd= comcode2str(header->request.opcode);
 179     if (cmd != NULL)
 180       fprintf(stderr, "post_execute from %p: %s\n", cookie, cmd);
 181     else
 182       fprintf(stderr, "post_execute from %p: 0x%02x\n", cookie, header->request.opcode);
 183   }
 184 }
 185
 186 /**
 187  * Callback handler for all unknown commands.
 188  * Send an unknown command back to the client
 189  */
 190 static protocol_binary_response_status unknown(const void *cookie,
 191                                                protocol_binary_request_header *header,
 192                                                memcached_binary_protocol_raw_response_handler response_handler)
 193 {
 194   protocol_binary_response_no_extras response= {
 195     .message= {
 196       .header.response= {
 197         .magic= PROTOCOL_BINARY_RES,
 198         .opcode= header->request.opcode,
 199         .status= htons(PROTOCOL_BINARY_RESPONSE_UNKNOWN_COMMAND),
 200         .opaque= header->request.opaque
 201       }
 202     }
 203   };
 204
 205   return response_handler(cookie, header, (void*)&response);
 206 }
 207
 208 static void work(void);
 209
 210 /**
 211  * Program entry point. Bind to the specified port(s) and serve clients
 212  *
 213  * @param argc number of items in the argument vector
 214  * @param argv argument vector
 215  * @return 0 on success, 1 otherwise
 216  */
 217 int main(int argc, char **argv)
 218 {
 219   bool port_specified= false;
 220   int cmd;
 221   struct memcached_binary_protocol_callback_st *interface= &interface_v0_impl;
 222
 223   while ((cmd= getopt(argc, argv, "v1p:?")) != EOF)
 224   {
 225     switch (cmd) {
 226     case '1':
 227       interface= &interface_v1_impl;
 228       break;
 229     case 'p':
 230       port_specified= true;
 231       (void)server_socket(optarg);
 232       break;
 233     case 'v':
 234       verbose= true;
 235       break;
 236     case '?':  /* FALLTHROUGH */
 237     default:
 238       (void)fprintf(stderr, "Usage: %s [-p port] [-v] [-1]\n", argv[0]);
 239       return 1;
 240     }
 241   }
 242
 243   if (!initialize_storage())
 244   {
 245     /* Error message already printed */
 246     return 1;
 247   }
 248
 249   if (!port_specified)
 250     (void)server_socket("9999");
 251
 252   if (num_server_sockets == 0)
 253   {
 254     fprintf(stderr, "I don't have any server sockets\n");
 255     return 1;
 256   }
 257
 258   /*
 259    * Create and initialize the handles to the protocol handlers. I want
 260    * to be able to trace the traffic throught the pre/post handlers, and
 261    * set up a common handler for unknown messages
 262    */
 263   interface->pre_execute= pre_execute;
 264   interface->post_execute= post_execute;
 265   interface->unknown= unknown;
 266
 267   struct memcached_protocol_st *protocol_handle;
 268   if ((protocol_handle= memcached_protocol_create_instance()) == NULL)
 269   {
 270     fprintf(stderr, "Failed to allocate protocol handle\n");
 271     return 1;
 272   }
 273
 274   memcached_binary_protocol_set_callbacks(protocol_handle, interface);
 275   memcached_binary_protocol_set_pedantic(protocol_handle, true);
 276
 277   for (int xx= 0; xx < num_server_sockets; ++xx)
 278     socket_userdata_map[server_sockets[xx]]= protocol_handle;
 279
 280   /* Serve all of the clients */
 281   work();
 282
 283   /* NOTREACHED */
 284   return 0;
 285 }
 286
 287 static void work(void) {
 288 #define MAX_SERVERS_TO_POLL 100
 289   struct pollfd fds[MAX_SERVERS_TO_POLL];
 290   int max_poll;
 291
 292   for (max_poll= 0; max_poll < num_server_sockets; ++max_poll)
 293   {
 294     fds[max_poll].events= POLLIN;
 295     fds[max_poll].revents= 0;
 296     fds[max_poll].fd= server_sockets[max_poll];
 297     ++max_poll;
 298   }
 299
 300   while (true)
 301   {
 302     int err= poll(fds, (nfds_t)max_poll, -1);
 303
 304     if (err == 0 || (err == -1 && errno != EINTR))
 305     {
 306       perror("poll() failed");
 307       abort();
 308     }
 309
 310     /* find the available filedescriptors */
 311     for (int x= max_poll - 1; x > -1 && err > 0; --x)
 312     {
 313       if (fds[x].revents != 0)
 314       {
 315         --err;
 316         if (x < num_server_sockets)
 317         {
 318           /* accept new client */
 319           struct sockaddr_storage addr;
 320           socklen_t addrlen= sizeof(addr);
 321           int sock= accept(fds[x].fd, (struct sockaddr *)&addr,
 322                            &addrlen);
 323
 324           if (sock == -1)
 325           {
 326             perror("Failed to accept client");
 327             continue;
 328           }
 329
 330           struct memcached_protocol_st *protocol;
 331           protocol= socket_userdata_map[fds[x].fd];
 332
 333           struct memcached_protocol_client_st* c;
 334           c= memcached_protocol_create_client(protocol, sock);
 335           if (c == NULL)
 336           {
 337             fprintf(stderr, "Failed to create client\n");
 338             close(sock);
 339           }
 340           else
 341           {
 342             socket_userdata_map[sock]= c;
 343             fds[max_poll].events= POLLIN;
 344             fds[max_poll].revents= 0;
 345             fds[max_poll].fd= sock;
 346             ++max_poll;
 347           }
 348         }
 349         else
 350         {
 351           /* drive the client */
 352           struct memcached_protocol_client_st* c;
 353           c= socket_userdata_map[fds[x].fd];
 354           assert(c != NULL);
 355           fds[max_poll].events= 0;
 356
 357           switch (memcached_protocol_client_work(c))
 358           {
 359           case WRITE_EVENT:
 360           case READ_WRITE_EVENT:
 361             fds[max_poll].events= POLLOUT;
 362             /* FALLTHROUGH */
 363           case READ_EVENT:
 364             fds[max_poll].events |= POLLIN;
 365             break;
 366           case ERROR_EVENT:
 367           default: /* ERROR or unknown state.. close */
 368             memcached_protocol_client_destroy(c);
 369             close(fds[x].fd);
 370             fds[x].events= 0;
 371
 372             if (x != max_poll - 1)
 373               memmove(fds + x, fds + x + 1, (size_t)(max_poll - x));
 374
 375             --max_poll;
 376           }
 377         }
 378       }
 379     }
 380   }
 381 }