Make ICC profile management thread safe.

The change to ref_count of profiles needs to be protected by a lock if
the profile ref_count could be changed by another thread. Also when
decrementing the ref_count to 0, we cannot free the lock until after
the profile has been unlocked.

New routine gsicc_adjust_profile_rc replaces old (not threadsafe) function
gsicc_profile_reference.

Also add tracing "cname" to the RC_ADJUST_ macro to aid in debugging
with -Z^ debug flag.

Testing had revealed race conditions which are now fixed (eliminate use
of semaphores).

This also changes the gsicc_lcms2art.c interface functions to keep a
list of transforms configured to have differing buffer formats that
include alpha, planar IN/OUT, big_endian IN/OUT, bytes_per_component
IN/OUT which are cloned as needed by threads.

Change gscms_is_threadsafe to return "true" in gsicc_lcms2art.c

TBD: If a link fails to build a thread may hang waiting for the link
profile to become valid if it was not the thread that was building it.
Not a new condition, but exposed when gscms_is_threadsafe returns true.

TBD: Fix error handling / clean-up when links fail to build. Also not
new, but is needed to prevent leaks, and possibly hang conditions.

1 files changed, 4 insertions, 10 deletions

diff --git a/base/gsicc_nocm.c b/base/gsicc_nocm.c
index ea24e9fc7..4f0c0f67e 100644
--- a/base/gsicc_nocm.c
+++ b/base/gsicc_nocm.c
@@ -389,8 +389,7 @@ gsicc_nocm_get_link(const gs_gstate *pgs, gx_device *dev,
         return NULL;
 
     /* Now compute the link contents */
-    /* Lock the cache as we alter the procs */
-    gx_monitor_enter(pgs->icc_link_cache->lock);
+    /* We (this thread) owns the lock on the new link just created. */
 
     result->procs.map_buffer = gsicc_nocm_transform_color_buffer;
     result->procs.map_color = gsicc_nocm_transform_color;
@@ -437,7 +436,6 @@ gsicc_nocm_get_link(const gs_gstate *pgs, gx_device *dev,
     } else {
         result->is_identity = false;
     }
-    result->valid = true;
     if (nocm_link->num_in == 4)
         data_cs = gsCMYK;
     else if (nocm_link->num_in == 1)
@@ -448,13 +446,9 @@ gsicc_nocm_get_link(const gs_gstate *pgs, gx_device *dev,
     if (pageneutralcolor && nocm_link->num_in != 1) {
         gsicc_mcm_set_link(result);
     }
-
-    /* Now release any tasks/threads waiting for these contents */
-    while (result->num_waiting > 0) {
-        gx_semaphore_signal(result->wait);
-        result->num_waiting--;
-    }
-    gx_monitor_leave(pgs->icc_link_cache->lock);	/* done with updating, let everyone run */
+    result->valid = true;
+    /* Now release any tasks/threads waiting for these contents by unlocking */
+    gx_monitor_leave(result->lock);	/* done with updating, let everyone run */
 
     return result;
 }