cgi-fcgi-interp: new garbage collection approach, spec (more)

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

diff --git a/cprogs/cgi-fcgi-interp.c b/cprogs/cgi-fcgi-interp.c
index 27327743b0cc361ec4a77efe0148a56bb7f4203a..602ffa62d274a8165a95b3ee65dfed0a911c478b 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.
@@ -68,7 +76,7 @@
  *   ~/.cgi-fcgi-interp/<node>/
  * and inside there uses these paths
  *   s<ident>
- *   g<inum>
+ *   l<ident>    used to lock around garbage collection
  *
  * If -M<ident> is not specified then an initial substricg of the
  * lowercase hex of the sha256 of the <script> (ie, our argv[1]) is
@@ -90,10 +98,22 @@
  *  - 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 -c<check-interval> \
+ *                --stage2 <was-stderr> <socket> \
+ *                <interp> <script>
+ *
+ * --stage2 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"
@@ -346,12 +366,62 @@ 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/%lu.%lu", run_base,
+    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);
 }