src/unlinkd.cc

   1
   2 /*
   3  * $Id$
   4  *
   5  * DEBUG: section 2     Unlink Daemon
   6  * AUTHOR: Duane Wessels
   7  *
   8  * SQUID Web Proxy Cache          http://www.squid-cache.org/
   9  * ----------------------------------------------------------
  10  *
  11  *  Squid is the result of efforts by numerous individuals from
  12  *  the Internet community; see the CONTRIBUTORS file for full
  13  *  details.   Many organizations have provided support for Squid's
  14  *  development; see the SPONSORS file for full details.  Squid is
  15  *  Copyrighted (C) 2001 by the Regents of the University of
  16  *  California; see the COPYRIGHT file for full details.  Squid
  17  *  incorporates software developed and/or copyrighted by other
  18  *  sources; see the CREDITS file for full details.
  19  *
  20  *  This program is free software; you can redistribute it and/or modify
  21  *  it under the terms of the GNU General Public License as published by
  22  *  the Free Software Foundation; either version 2 of the License, or
  23  *  (at your option) any later version.
  24  *
  25  *  This program is distributed in the hope that it will be useful,
  26  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  27  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  28  *  GNU General Public License for more details.
  29  *
  30  *  You should have received a copy of the GNU General Public License
  31  *  along with this program; if not, write to the Free Software
  32  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  33  *
  34  */
  35
  36 #include "squid.h"
  37 #include "SquidTime.h"
  38 #include "fde.h"
  39 #include "xusleep.h"
  40
  41 /* This code gets linked to Squid */
  42
  43 static int unlinkd_wfd = -1;
  44 static int unlinkd_rfd = -1;
  45
  46 static void * hIpc;
  47 static pid_t pid;
  48
  49 #define UNLINKD_QUEUE_LIMIT 20
  50
  51 void
  52 unlinkdUnlink(const char *path)
  53 {
  54     char buf[MAXPATHLEN];
  55     int l;
  56     int x;
  57     static int queuelen = 0;
  58
  59     if (unlinkd_wfd < 0) {
  60         debug_trap("unlinkdUnlink: unlinkd_wfd < 0");
  61         safeunlink(path, 0);
  62         return;
  63     }
  64
  65     /*
  66      * If the queue length is greater than our limit, then we pause
  67      * for a small amount of time, hoping that unlinkd has some
  68      * feedback for us.  Maybe it just needs a slice of the CPU's
  69      * time.
  70      */
  71     if (queuelen >= UNLINKD_QUEUE_LIMIT) {
  72 #if defined(USE_EPOLL) || defined(USE_KQUEUE)
  73         /*
  74          * DPW 2007-04-23
  75          * We can't use fd_set when using epoll() or kqueue().  In
  76          * these cases we block for 10 ms.
  77          */
  78         xusleep(10000);
  79 #else
  80         /*
  81          * DPW 2007-04-23
  82          * When we can use select, block for up to 100 ms.
  83          */
  84         struct timeval to;
  85         fd_set R;
  86         FD_ZERO(&R);
  87         FD_SET(unlinkd_rfd, &R);
  88         to.tv_sec = 0;
  89         to.tv_usec = 100000;
  90         select(unlinkd_rfd + 1, &R, NULL, NULL, &to);
  91 #endif
  92     }
  93
  94     /*
  95     * If there is at least one outstanding unlink request, then
  96     * try to read a response.  If there's nothing to read we'll
  97     * get an EWOULDBLOCK or whatever.  If we get a response, then
  98     * decrement the queue size by the number of newlines read.
  99     */
 100     if (queuelen > 0) {
 101         int x;
 102         int i;
 103         char rbuf[512];
 104         x = read(unlinkd_rfd, rbuf, 511);
 105
 106         if (x > 0) {
 107             rbuf[x] = '\0';
 108
 109             for (i = 0; i < x; i++)
 110                 if ('\n' == rbuf[i])
 111                     queuelen--;
 112
 113             assert(queuelen >= 0);
 114         }
 115     }
 116
 117     l = strlen(path);
 118     assert(l < MAXPATHLEN);
 119     xstrncpy(buf, path, MAXPATHLEN);
 120     buf[l++] = '\n';
 121     x = write(unlinkd_wfd, buf, l);
 122
 123     if (x < 0) {
 124         debugs(2, 1, "unlinkdUnlink: write FD " << unlinkd_wfd << " failed: " << xstrerror());
 125         safeunlink(path, 0);
 126         return;
 127     } else if (x != l) {
 128         debugs(2, 1, "unlinkdUnlink: FD " << unlinkd_wfd << " only wrote " << x << " of " << l << " bytes");
 129         safeunlink(path, 0);
 130         return;
 131     }
 132
 133     statCounter.unlink.requests++;
 134     /*
 135     * Increment this syscalls counter here, even though the syscall
 136     * is executed by the helper process.  We try to be consistent
 137     * in counting unlink operations.
 138     */
 139     statCounter.syscalls.disk.unlinks++;
 140     queuelen++;
 141 }
 142
 143 void
 144 unlinkdClose(void)
 145 #ifdef _SQUID_MSWIN_
 146 {
 147
 148     if (unlinkd_wfd > -1) {
 149         debugs(2, 1, "Closing unlinkd pipe on FD " << unlinkd_wfd);
 150         shutdown(unlinkd_wfd, SD_BOTH);
 151         comm_close(unlinkd_wfd);
 152
 153         if (unlinkd_wfd != unlinkd_rfd)
 154             comm_close(unlinkd_rfd);
 155
 156         unlinkd_wfd = -1;
 157
 158         unlinkd_rfd = -1;
 159     } else
 160         debugs(2, 0, "unlinkdClose: WARNING: unlinkd_wfd is " << unlinkd_wfd);
 161
 162     if (hIpc) {
 163         if (WaitForSingleObject(hIpc, 5000) != WAIT_OBJECT_0) {
 164             getCurrentTime();
 165             debugs(2, 1, "unlinkdClose: WARNING: (unlinkd," << pid << "d) didn't exit in 5 seconds");
 166         }
 167
 168         CloseHandle(hIpc);
 169     }
 170 }
 171 #else
 172 {
 173
 174     if (unlinkd_wfd < 0)
 175         return;
 176
 177     debugs(2, 1, "Closing unlinkd pipe on FD " << unlinkd_wfd);
 178
 179     file_close(unlinkd_wfd);
 180
 181     if (unlinkd_wfd != unlinkd_rfd)
 182         file_close(unlinkd_rfd);
 183
 184     unlinkd_wfd = -1;
 185
 186     unlinkd_rfd = -1;
 187 }
 188
 189 #endif
 190
 191 void
 192 unlinkdInit(void)
 193 {
 194     const char *args[2];
 195     IpAddress localhost;
 196
 197     args[0] = "(unlinkd)";
 198     args[1] = NULL;
 199     localhost.SetLocalhost();
 200
 201     pid = ipcCreate(
 202 #if USE_POLL && defined(_SQUID_OSF_)
 203               /* pipes and poll() don't get along on DUNIX -DW */
 204               IPC_STREAM,
 205 #elif defined(_SQUID_MSWIN_)
 206               /* select() will fail on a pipe */
 207               IPC_TCP_SOCKET,
 208 #else
 209               /* We currently need to use FIFO.. see below */
 210               IPC_FIFO,
 211 #endif
 212               Config.Program.unlinkd,
 213               args,
 214               "unlinkd",
 215               localhost,
 216               &unlinkd_rfd,
 217               &unlinkd_wfd,
 218               &hIpc);
 219
 220     if (pid < 0)
 221         fatal("Failed to create unlinkd subprocess");
 222
 223     xusleep(250000);
 224
 225     fd_note(unlinkd_wfd, "squid -> unlinkd");
 226
 227     fd_note(unlinkd_rfd, "unlinkd -> squid");
 228
 229     commSetTimeout(unlinkd_rfd, -1, NULL, NULL);
 230
 231     commSetTimeout(unlinkd_wfd, -1, NULL, NULL);
 232
 233     /*
 234     * unlinkd_rfd should already be non-blocking because of
 235     * ipcCreate.  We change unlinkd_wfd to blocking mode because
 236     * we never want to lose an unlink request, and we don't have
 237     * code to retry if we get EWOULDBLOCK.  Unfortunately, we can
 238     * do this only for the IPC_FIFO case.
 239     */
 240     assert(fd_table[unlinkd_rfd].flags.nonblocking);
 241
 242     if (FD_PIPE == fd_table[unlinkd_wfd].type)
 243         commUnsetNonBlocking(unlinkd_wfd);
 244
 245     debugs(2, 1, "Unlinkd pipe opened on FD " << unlinkd_wfd);
 246
 247 #ifdef _SQUID_MSWIN_
 248
 249     debugs(2, 4, "Unlinkd handle: 0x" << std::hex << hIpc << std::dec << ", PID: " << pid);
 250
 251 #endif
 252
 253 }