cgi-fcgi-interp: new garbage collection approach, spec

[chiark-utils.git] / cprogs / cgi-fcgi-interp.c

diff --git a/cprogs/cgi-fcgi-interp.c b/cprogs/cgi-fcgi-interp.c
index 1d88f50294997bc5cced3d4c3abc839bfa29cb79..bfcfd9afe546e0719ceb519cf24cd2f7e7e1698a 100644 (file)
--- a/cprogs/cgi-fcgi-interp.c
+++ b/cprogs/cgi-fcgi-interp.c
@@ -50,6 +50,14 @@
  *         speedy, the specified number of servers is started
  *         right away.)  The default is 4.
  *
+ *  -c<interval>
+ *         Stale server check interval, in seconds.  The worker
+ *         process group will get a SIGTERM when it is no longer
+ *         needed to process new requests.  Ideally it would continue
+ *         to serve any existing requests.  The SIGTERM will arrive no
+ *         earlier than <interval> after the last request arrived at
+ *         the containing webserver.  Default is 300.
+ *
  *  -D
  *         Debug mode.  Do not actually run program.  Instead, print
  *         out what we would do.
@@ -90,10 +98,20 @@
  *  - check for and maybe create <base>
  *  - stat and lstat the <script>
  *  - stat the socket and check its timestamp
- *       if it is too old, rename it to g<inum>.<pid> (where
- *       <inum> and <pid> are in decimal)
- *       and run garbage collection
- *  - run  cgi-fcgi -connect SOCKET SCRIPT
+ *       if it is too old, unlink it
+ *  - dup2 stderr, mark no cloexec
+ *  - run  cgi-fcgi -connect SOCKET \
+ *        cgi-fcgi-interp --stage2 <was-stderr> <socket> <interp> <script>
+ *
+ * -E<was-stderr> does this:
+ *  - dup2 <was-stderr> to fd 2
+ *  - open /dev/null and expect fd 1 (and if not, close it)
+ *  - become a new process group
+ *  - lstat <socket> to find its inum, mtime
+ *  - fork/exec <interp> <script>
+ *  - periodically lstat <socket> and
+ *      if inum, mtime have changed
+ *      kill process group (at second iteration)
  */
 
 #include "common.h"
@@ -164,6 +182,7 @@ static const struct cmdinfo cmdinfos[]= {
 
 static uid_t us;
 static const char *run_base, *script, *socket_path;
+static struct stat sock_stab;
 
 static bool find_run_base_var_run(void) {
   struct stat stab;
@@ -307,12 +326,18 @@ static void find_socket_path(void) {
             ((tvp)->tv_sec cmp (uvp)->tv_sec))
 #endif /*timespeccmp*/
 
+
+
 static bool stab_isnewer(const struct stat *a, const struct stat *b) {
-  return 0;
+#ifdef st_mtime
+  return timespeccmp(&a->st_mtim, &b->st_mtim, >);
+#else
+  return a->st_mtime > &b->st_mtime;
+#endif
 }
 
 static bool check_garbage(void) {
-  struct stat sock_stab, script_stab;
+  struct stat script_stab;
   int r;
 
   r = lstat(script, &script_stab);
@@ -339,6 +364,65 @@ static bool check_garbage(void) {
   return 0;
 }
 
+static void tidy_1_garbage(const char *leaf) {
+  int r;
+  struct sockaddr_un sun;
+
+  int fd = -1;
+
+  memset(&sun,0,sizeof(sun));
+  sun.sun_family = AF_UNIX;
+  r = snprintf(sun.sun_path, sizeof(sun.sun_path), "%s/%s", run_base, leaf);
+  if (r >= sizeof(sun_path))
+    goto cannot;
+
+  fd = socket(AF_UNIX, SOCK_STREAM, 0);
+  if (fd<0) err("create socket for tidying garbage");
+
+  r = fcntl(fd, F_SETFL, O_NONBLOCK);
+  if (r<0) err("set garbage socket nonblocking");
+
+  r = connect(fd, &sun, sizeof(sun));
+  if (r) {
+    if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
+      goto cannot;
+    if (errno != EINPROGRESS)
+      err("connect to garbage socket (%s)", sun.sun_path);
+    /* well, EINPROGRESS, let's just carry on and hope write works */
+  }
+
+  r = write(
+       
+
+static void tidy_garbage(void) {
+  const char *this_garbage =
+    m_asprintf("%s/g%lu.%lu", run_base,
+              (unsigned long)sock_stab.st_ino,
+              (unsigned long)getpid());
+
+  r = rename(socket_path, this_garbage);
+  if (r) {
+    if (!(errno == ENOENT))
+      err("rename socket from old runner (from %s to %s)",
+         socket_path, this_garbage);
+  }
+
+  DIR *d = opendir(run_base);
+  if (!d) err("open run directory (%d) to clean up garbage", run_base);
+  struct dirent *de;
+  while ((errno = 0, de = readdir(d))) {
+    if (de->d_name[0] != 'g')
+      continue;
+    tidy_1_garbage(de->d_name);
+  }
+  if (errno) err("read run directory (%d) to clean up garbage", run_base);
+  /* 
+  (void)r;
+  if (r) {
+
+  printf("this_garb: %s\n", this_garbage);
+}
+
 static void shbang_opts(const char *const **argv_io,
                        const struct cmdinfo *cmdinfos) {
   myopt(argv_io, cmdinfos);
@@ -389,13 +473,18 @@ int main(int argc, const char *const *argv) {
 
   find_socket_path();
 
-  check_garbage();
+  bool havegarbage = check_garbage();
 
   if (debugmode) {
     printf("socket: %s\n",socket_path);
     printf("interp: %s\n",interp);
     printf("script: %s\n",script);
+    printf("garbage: %d\n",havegarbage);
+    exit(0);
   }
 
+  if (havegarbage)
+    tidy_garbage();
+
   exit(0);
 }