[t:4283] Closes #4283 Detect begin checkpoint in critical regions.

git-svn-id: file:///svn/toku/tokudb@37926 c7de825b-a66e-492c-adef-691d508d4ae1

newbrt/cachetable.c

@@ -169,6 +169,8 @@ struct cachetable {
     KIBBUTZ kibbutz;              // another pool of worker threads and jobs to do asynchronously.  
 
     LSN lsn_of_checkpoint_in_progress;
+    uint64_t checkpoint_sequence_number; // just a free-running sequence number, used for detecting threadsafety bugs
+    uint64_t checkpoint_prohibited;   // nonzero when checkpoints are prohibited,  used for detecting threadsafety bugs
     u_int32_t checkpoint_num_files;  // how many cachefiles are in the checkpoint
     u_int32_t checkpoint_num_txns;   // how many transactions are in the checkpoint
     PAIR pending_head;           // list of pairs marked with checkpoint_pending
@@ -196,6 +198,18 @@ struct cachetable {
     int64_t size_cachepressure;
 };
 
+// Code bracketed with {BEGIN_CRITICAL_REGION; ... END_CRITICAL_REGION;} macros
+// are critical regions in which a checkpoint is not permitted to begin.
+#define BEGIN_CRITICAL_REGION {uint64_t cp_seqnum = ct->checkpoint_sequence_number; \
+	__sync_fetch_and_add(&ct->checkpoint_prohibited, 1);
+
+#define END_CRITICAL_REGION invariant(cp_seqnum == ct->checkpoint_sequence_number); \
+	invariant(ct->checkpoint_prohibited > 0); \
+        __sync_fetch_and_sub(&ct->checkpoint_prohibited, 1); }
+
+
+
+
 // Lock the cachetable
 static inline void cachefiles_lock(CACHETABLE ct) {
     int r = toku_pthread_mutex_lock(&ct->cachefiles_mutex); resource_assert_zero(r);
@@ -1840,6 +1854,7 @@ void toku_checkpoint_pairs(
         );
 }
 
+
 int toku_cachetable_put_with_dep_pairs(
     CACHEFILE cachefile, 
     CACHETABLE_GET_KEY_AND_FULLHASH get_key_and_fullhash,
@@ -1879,8 +1894,12 @@ int toku_cachetable_put_with_dep_pairs(
     // cachetable_put_internal does not release the cachetable lock
     //
     cachetable_wait_write(ct);
+    int rval;
+    {
+	BEGIN_CRITICAL_REGION;
+
 	get_key_and_fullhash(key, fullhash, get_key_and_fullhash_extra);
-    int r = cachetable_put_internal(
+	rval = cachetable_put_internal(
 				       cachefile,
 				       *key,
 				       *fullhash,
@@ -1906,8 +1925,10 @@ int toku_cachetable_put_with_dep_pairs(
 				   dependent_dirty
 				   );
 
+	END_CRITICAL_REGION;
+    }
     cachetable_unlock(ct);
-    return r;
+    return rval;
 }
 
 
@@ -2176,8 +2197,12 @@ got_value:
     *value = p->value;
     if (sizep) *sizep = p->attr.size;
 
+
+    {
+	BEGIN_CRITICAL_REGION;
+
 	//
-    // A checkpoint cannot begin while we are checking dependent pairs or pending bits. 
+	// A checkpoint must not begin while we are checking dependent pairs or pending bits. 
 	// Here is why.
 	//
 	// Now that we have all of the locks on the pairs we 
@@ -2211,6 +2236,9 @@ got_value:
 				   dependent_dirty
 				   );
 
+	END_CRITICAL_REGION;
+    }
+
     r = maybe_flush_some(ct, 0);
     cachetable_unlock(ct);
     WHEN_TRACE_CT(printf("%s:%d did fetch: cachtable_get_and_pin(%lld)--> %p\n", __FILE__, __LINE__, key, *value));
@@ -3111,6 +3139,8 @@ toku_cachetable_begin_checkpoint (CACHETABLE ct, TOKULOGGER logger) {
             assert(r==0);
         }
 	cachetable_lock(ct);
+	invariant(ct->checkpoint_prohibited == 0);  // detect threadsafety bugs
+	ct->checkpoint_sequence_number++; 
 	//Initialize accountability counters
 	ct->checkpoint_num_files = 0;
 	ct->checkpoint_num_txns  = 0;