mgmt: checksumming is interruptible during thread shutdown

We want to yield dying threads as soon as possible during
thread shutdown, so we check the quit flag and yield the
running thread to trigger a MOG_NEXT_ACTIVE.

5 files changed, 13 insertions, 1 deletions

diff --git a/cmogstored.h b/cmogstored.h
index 4162931..487a70d 100644
--- a/cmogstored.h
+++ b/cmogstored.h
@@ -426,6 +426,7 @@ char *mog_canonpath_die(const char *path, enum canonicalize_mode_t canon_mode);
 
 /* thrpool.c */
 void mog_thr_test_quit(void);
+bool mog_thr_prepare_quit(void) MOG_CHECK;
 void mog_thrpool_start(struct mog_thrpool *, size_t n,
                        void *(*start_fn)(void *), void *arg);
 void mog_thrpool_quit(struct mog_thrpool *, struct mog_queue *);
diff --git a/digest.c b/digest.c
index 2f2b6d7..090c695 100644
--- a/digest.c
+++ b/digest.c
@@ -28,6 +28,8 @@ enum mog_digest_next mog_digest_read(struct mog_digest *digest, int fd)
 
                 if (r > 0) { /* most likely */
                         gc_hash_write(digest->ctx, r, buf);
+                        if (mog_thr_prepare_quit())
+                                return MOG_DIGEST_YIELD;
                 } else if (r == 0) {
                         /* wait for user to call mog_digest_hex() */
                         return MOG_DIGEST_EOF;
diff --git a/digest.h b/digest.h
index bef35b8..c037fcd 100644
--- a/digest.h
+++ b/digest.h
@@ -4,6 +4,7 @@
  */
 enum mog_digest_next {
         MOG_DIGEST_CONTINUE = 0,
+        MOG_DIGEST_YIELD,
         MOG_DIGEST_EOF,
         MOG_DIGEST_ERROR
 };
diff --git a/mgmt.c b/mgmt.c
index 4b8ef8b..aaf96a5 100644
--- a/mgmt.c
+++ b/mgmt.c
@@ -34,7 +34,9 @@ static void mgmt_digest_step(struct mog_fd *mfd)
         assert(mgmt->wbuf == NULL && "wbuf should be NULL here");
 
         switch (next) {
-        case MOG_DIGEST_CONTINUE: return;
+        case MOG_DIGEST_CONTINUE:
+        case MOG_DIGEST_YIELD:
+                return;
         case MOG_DIGEST_EOF:
                 mog_mgmt_fn_digest_emit(mgmt);
                 break;
diff --git a/thrpool.c b/thrpool.c
index 9cf8196..918fef8 100644
--- a/thrpool.c
+++ b/thrpool.c
@@ -66,6 +66,12 @@ void mog_thr_test_quit(void)
         }
 }
 
+bool mog_thr_prepare_quit(void)
+{
+        /* no barriers or atomic instructions, this is just a hint */
+        return !!mog_do_quit;
+}
+
 /*
  * we no longer rely on pthreads cancellation, so our explicit checks for
  * thread quitting requires us to continuously signal a thread for death