src/lib-old-stats/stats-connection.c

/* Copyright (c) 2011-2018 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "ioloop.h"
#include "str.h"
#include "master-service.h"
#include "stats-connection.h"

#include <unistd.h>
#include <fcntl.h>

#define STATS_EAGAIN_WARN_INTERVAL_SECS 30

struct stats_connection {
    int refcount;

    int fd;
    char *path;

    bool open_failed;
    time_t next_warning_timestamp;
};

static bool stats_connection_open(struct stats_connection *conn)
{
    if (conn->open_failed)
        return FALSE;

    conn->fd = open(conn->path, O_WRONLY | O_NONBLOCK);
    if (conn->fd == -1) {
        i_error("stats: open(%s) failed: %m", conn->path);
        conn->open_failed = TRUE;
        return FALSE;
    }
    return TRUE;
}

struct stats_connection *
stats_connection_create(const char *path)
{
    struct stats_connection *conn;

    conn = i_new(struct stats_connection, 1);
    conn->refcount = 1;
    conn->path = i_strdup(path);
    (void)stats_connection_open(conn);
    return conn;
}

void stats_connection_ref(struct stats_connection *conn)
{
    conn->refcount++;
}

void stats_connection_unref(struct stats_connection **_conn)
{
    struct stats_connection *conn = *_conn;

    i_assert(conn->refcount > 0);
    if (--conn->refcount > 0)
        return;

    *_conn = NULL;
    i_close_fd_path(&conn->fd, conn->path);
    i_free(conn->path);
    i_free(conn);
}

int stats_connection_send(struct stats_connection *conn, const string_t *str)
{
    static bool pipe_warned = FALSE;
    ssize_t ret;

    /* if master process has been stopped (and restarted), don't even try
       to notify the stats process anymore. even if one exists, it doesn't
       know about us. */
    if (master_service_is_master_stopped(master_service))
        return -1;

    if (conn->fd == -1) {
        if (!stats_connection_open(conn))
            return -1;
        i_assert(conn->fd != -1);
    }

    if (str_len(str) > PIPE_BUF && !pipe_warned) {
        i_warning("stats update sent more bytes that PIPE_BUF "
              "(%"PRIuSIZE_T" > %u), this may break statistics",
              str_len(str), (unsigned int)PIPE_BUF);
        pipe_warned = TRUE;
    }

    ret = write(conn->fd, str_data(str), str_len(str));
    if (ret == (ssize_t)str_len(str)) {
        /* success */
        return 0;
    } else if (ret < 0 && errno == EAGAIN) {
        /* stats process is busy */
        if (ioloop_time > conn->next_warning_timestamp) {
            i_warning("write(%s) failed: %m (stats process is busy)", conn->path);
            conn->next_warning_timestamp = ioloop_time +
                STATS_EAGAIN_WARN_INTERVAL_SECS;
        }
        return -1;
    } else {
        /* error - reconnect */
        if (ret < 0) {
            /* don't log EPIPE errors. they can happen when
               Dovecot is stopped. */
            if (errno != EPIPE)
                i_error("write(%s) failed: %m", conn->path);
        } else if ((size_t)ret != str_len(str))
            i_error("write(%s) wrote partial update", conn->path);
        if (close(conn->fd) < 0)
            i_error("close(%s) failed: %m", conn->path);
        conn->fd = -1;
        return -1;
    }
}