memcached.c

memcached是一个高性能的分布式的内存对象缓存系统

        struct mallinfo info;
        char *pos = temp;

        info = mallinfo();
        pos += sprintf(pos, "STAT arena_size %d\r\n", info.arena);
        pos += sprintf(pos, "STAT free_chunks %d\r\n", info.ordblks);
        pos += sprintf(pos, "STAT fastbin_blocks %d\r\n", info.smblks);
        pos += sprintf(pos, "STAT mmapped_regions %d\r\n", info.hblks);
        pos += sprintf(pos, "STAT mmapped_space %d\r\n", info.hblkhd);
        pos += sprintf(pos, "STAT max_total_alloc %d\r\n", info.usmblks);
        pos += sprintf(pos, "STAT fastbin_space %d\r\n", info.fsmblks);
        pos += sprintf(pos, "STAT total_alloc %d\r\n", info.uordblks);
        pos += sprintf(pos, "STAT total_free %d\r\n", info.fordblks);
        pos += sprintf(pos, "STAT releasable_space %d\r\nEND", info.keepcost);
        out_string(c, temp);
        return;
    }
#endif /* HAVE_STRUCT_MALLINFO */
#endif /* HAVE_MALLOC_H */

    if (strcmp(subcommand, "maps") == 0) {
        char *wbuf;
        int wsize = 8192; /* should be enough */
        int fd;
        int res;

        if (!(wbuf = (char *)malloc(wsize))) {
            out_string(c, "SERVER_ERROR out of memory");
            return;
        }

        fd = open("/proc/self/maps", O_RDONLY);
        if (fd == -1) {
            out_string(c, "SERVER_ERROR cannot open the maps file");
            free(wbuf);
            return;
        }

        res = read(fd, wbuf, wsize - 6);  /* 6 = END\r\n\0 */
        if (res == wsize - 6) {
            out_string(c, "SERVER_ERROR buffer overflow");
            free(wbuf); close(fd);
            return;
        }
        if (res == 0 || res == -1) {
            out_string(c, "SERVER_ERROR can't read the maps file");
            free(wbuf); close(fd);
            return;
        }
        memcpy(wbuf + res, "END\r\n", 6);
        c->write_and_free = wbuf;
        c->wcurr = wbuf;
        c->wbytes = res + 5; // Don't write the terminal '\0'
        conn_set_state(c, conn_write);
        c->write_and_go = conn_read;
        close(fd);
        return;
    }

    if (strcmp(subcommand, "cachedump") == 0) {

        char *buf;
        unsigned int bytes, id, limit = 0;

        if(ntokens < 5) {
            out_string(c, "CLIENT_ERROR bad command line");
            return;
        }

        id = strtoul(tokens[2].value, NULL, 10);
        limit = strtoul(tokens[3].value, NULL, 10);

        if(errno == ERANGE) {
            out_string(c, "CLIENT_ERROR bad command line format");
            return;
        }

        buf = item_cachedump(id, limit, &bytes);
        if (buf == 0) {
            out_string(c, "SERVER_ERROR out of memory");
            return;
        }

        c->write_and_free = buf;
        c->wcurr = buf;
        c->wbytes = bytes;
        conn_set_state(c, conn_write);
        c->write_and_go = conn_read;
        return;
    }

    if (strcmp(subcommand, "slabs") == 0) {
        int bytes = 0;
        char *buf = slabs_stats(&bytes);
        if (!buf) {
            out_string(c, "SERVER_ERROR out of memory");
            return;
        }
        c->write_and_free = buf;
        c->wcurr = buf;
        c->wbytes = bytes;
        conn_set_state(c, conn_write);
        c->write_and_go = conn_read;
        return;
    }

    if (strcmp(subcommand, "items") == 0) {
        char buffer[4096];
        item_stats(buffer, 4096);
        out_string(c, buffer);
        return;
    }

    if (strcmp(subcommand, "detail") == 0) {
        if (ntokens < 4)
            process_stats_detail(c, "");  /* outputs the error message */
        else
            process_stats_detail(c, tokens[2].value);
        return;
    }

    if (strcmp(subcommand, "sizes") == 0) {
        int bytes = 0;
        char *buf = item_stats_sizes(&bytes);
        if (! buf) {
            out_string(c, "SERVER_ERROR out of memory");
            return;
        }

        c->write_and_free = buf;
        c->wcurr = buf;
        c->wbytes = bytes;
        conn_set_state(c, conn_write);
        c->write_and_go = conn_read;
        return;
    }

    out_string(c, "ERROR");
}

/* ntokens is overwritten here... shrug.. */
static inline void process_get_command(conn *c, token_t *tokens, size_t ntokens) {
    char *key;
    size_t nkey;
    int i = 0;
    item *it;
    token_t *key_token = &tokens[KEY_TOKEN];

    assert(c != NULL);

    if (settings.managed) {
        int bucket = c->bucket;
        if (bucket == -1) {
            out_string(c, "CLIENT_ERROR no BG data in managed mode");
            return;
        }
        c->bucket = -1;
        if (buckets[bucket] != c->gen) {
            out_string(c, "ERROR_NOT_OWNER");
            return;
        }
    }

    do {
        while(key_token->length != 0) {

            key = key_token->value;
            nkey = key_token->length;

            if(nkey > KEY_MAX_LENGTH) {
                out_string(c, "CLIENT_ERROR bad command line format");
                return;
            }

            STATS_LOCK();
            stats.get_cmds++;
            STATS_UNLOCK();
            it = item_get(key, nkey);
            if (settings.detail_enabled) {
                stats_prefix_record_get(key, NULL != it);
            }
            if (it) {
                if (i >= c->isize) {
                    item **new_list = realloc(c->ilist, sizeof(item *) * c->isize * 2);
                    if (new_list) {
                        c->isize *= 2;
                        c->ilist = new_list;
                    } else break;
                }

                /*
                 * Construct the response. Each hit adds three elements to the
                 * outgoing data list:
                 *   "VALUE "
                 *   key
                 *   " " + flags + " " + data length + "\r\n" + data (with \r\n)
                 */
                if (add_iov(c, "VALUE ", 6) != 0 ||
                    add_iov(c, ITEM_key(it), it->nkey) != 0 ||
                    add_iov(c, ITEM_suffix(it), it->nsuffix + it->nbytes) != 0)
                    {
                        break;
                    }
                if (settings.verbose > 1)
                    fprintf(stderr, ">%d sending key %s\n", c->sfd, ITEM_key(it));

                /* item_get() has incremented it->refcount for us */
                STATS_LOCK();
                stats.get_hits++;
                STATS_UNLOCK();
                item_update(it);
                *(c->ilist + i) = it;
                i++;

            } else {
                STATS_LOCK();
                stats.get_misses++;
                STATS_UNLOCK();
            }

            key_token++;
        }

        /*
         * If the command string hasn't been fully processed, get the next set
         * of tokens.
         */
        if(key_token->value != NULL) {
            ntokens = tokenize_command(key_token->value, tokens, MAX_TOKENS);
            key_token = tokens;
        }

    } while(key_token->value != NULL);

    c->icurr = c->ilist;
    c->ileft = i;

    if (settings.verbose > 1)
        fprintf(stderr, ">%d END\n", c->sfd);
    add_iov(c, "END\r\n", 5);

    if (c->udp && build_udp_headers(c) != 0) {
        out_string(c, "SERVER_ERROR out of memory");
    }
    else {
        conn_set_state(c, conn_mwrite);
        c->msgcurr = 0;
    }
    return;
}

static void process_update_command(conn *c, token_t *tokens, const size_t ntokens, int comm) {
    char *key;
    size_t nkey;
    int flags;
    time_t exptime;
    int vlen;
    item *it;

    assert(c != NULL);

    if (tokens[KEY_TOKEN].length > KEY_MAX_LENGTH) {
        out_string(c, "CLIENT_ERROR bad command line format");
        return;
    }

    key = tokens[KEY_TOKEN].value;
    nkey = tokens[KEY_TOKEN].length;

    flags = strtoul(tokens[2].value, NULL, 10);
    exptime = strtol(tokens[3].value, NULL, 10);
    vlen = strtol(tokens[4].value, NULL, 10);

    if(errno == ERANGE || ((flags == 0 || exptime == 0) && errno == EINVAL)) {
        out_string(c, "CLIENT_ERROR bad command line format");
        return;
    }

    if (settings.detail_enabled) {
        stats_prefix_record_set(key);
    }

    if (settings.managed) {
        int bucket = c->bucket;
        if (bucket == -1) {
            out_string(c, "CLIENT_ERROR no BG data in managed mode");
            return;
        }
        c->bucket = -1;
        if (buckets[bucket] != c->gen) {
            out_string(c, "ERROR_NOT_OWNER");
            return;
        }
    }

    it = item_alloc(key, nkey, flags, realtime(exptime), vlen+2);

    if (it == 0) {
        if (! item_size_ok(nkey, flags, vlen + 2))
            out_string(c, "SERVER_ERROR object too large for cache");
        else
            out_string(c, "SERVER_ERROR out of memory");
        /* swallow the data line */
        c->write_and_go = conn_swallow;
        c->sbytes = vlen + 2;
        return;
    }

    c->item_comm = comm;
    c->item = it;
    c->ritem = ITEM_data(it);
    c->rlbytes = it->nbytes;
    conn_set_state(c, conn_nread);
}

static void process_arithmetic_command(conn *c, token_t *tokens, const size_t ntokens, const int incr) {
    char temp[32];
    item *it;
    unsigned int delta;
    char *key;
    size_t nkey;

    assert(c != NULL);

    if(tokens[KEY_TOKEN].length > KEY_MAX_LENGTH) {
        out_string(c, "CLIENT_ERROR bad command line format");
        return;
    }

    key = tokens[KEY_TOKEN].value;
    nkey = tokens[KEY_TOKEN].length;

    if (settings.managed) {
        int bucket = c->bucket;
        if (bucket == -1) {
            out_string(c, "CLIENT_ERROR no BG data in managed mode");
            return;
        }
        c->bucket = -1;
        if (buckets[bucket] != c->gen) {
            out_string(c, "ERROR_NOT_OWNER");
            return;
        }
    }

    delta = strtoul(tokens[2].value, NULL, 10);

    if(errno == ERANGE) {
        out_string(c, "CLIENT_ERROR bad command line format");
        return;
    }

    it = item_get(key, nkey);
    if (!it) {
        out_string(c, "NOT_FOUND");
        return;
    }

    out_string(c, add_delta(it, incr, delta, temp));
    item_remove(it);         /* release our reference */
}

/*
 * adds a delta value to a numeric item.
 *
 * it    item to adjust
 * incr  true to increment value, false to decrement
 * delta amount to adjust value by
 * buf   buffer for response string
 *
 * returns a response string to send back to the client.
 */
char *do_add_delta(item *it, int incr, unsigned int delta, char *buf) {
    char *ptr;
    unsigned int value;
    int res;

    ptr = ITEM_data(it);
    while ((*ptr != '\0') && (*ptr < '0' && *ptr > '9')) ptr++;    // BUG: can't be true

    value = strtol(ptr, NULL, 10);

    if(errno == ERANGE) {
        return "CLIENT_ERROR cannot increment or decrement non-numeric value";
    }

    if (incr != 0)
        value += delta;
    else {
        if (delta >= value) value = 0;
        else value -= delta;
    }
    snprintf(buf, 32, "%u", value);
    res = strlen(buf);
    if (res + 2 > it->nbytes) { /* need to realloc */
        item *new_it;
        new_it = do_item_alloc(ITEM_key(it), it->nkey, atoi(ITEM_suffix(it) + 1), it->exptime, res + 2 );
        if (new_it == 0) {
            return "SERVER_ERROR out of memory";
        }
        memcpy(ITEM_data(new_it), buf, res);
        memcpy(ITEM_data(new_it) + res, "\r\n", 3);
        do_item_replace(it, new_it);
        do_item_remove(new_it);       /* release our reference */
    } else { /* replace in-place */
        memcpy(ITEM_data(it), buf, res);
        memset(ITEM_data(it) + res, ' ', it->nbytes - res - 2);
    }

    return buf;
}

static void process_delete_command(conn *c, token_t *tokens, const size_t ntokens) {
    char *key;
    size_t nkey;
    item *it;
    time_t exptime = 0;

    assert(c != NULL);

    if (settings.managed) {
        int bucket = c->bucket;
        if (bucket == -1) {
            out_string(c, "CLIENT_ERROR no BG data in managed mode");
            return;
        }
        c->bucket = -1;
        if (buckets[bucket] != c->gen) {
            out_string(c, "ERROR_NOT_OWNER");
            return;
        }
    }

    key = tokens[KEY_TOKEN].value;
    nkey = tokens[KEY_TOKEN].length;

    if(nkey > KEY_MAX_LENGTH) {
        out_string(c, "CLIENT_ERROR bad command line format");
        return;
    }

    if(ntokens == 4) {
        exptime = strtol(tokens[2].value, NULL, 10);

        if(errno == ERANGE) {
            out_string(c, "CLIENT_ERROR bad command line format");
            return;
        }
    }

    if (settings.detail_enabled) {
        stats_prefix_record_delete(key);
    }