WT-2781 Don't take checkpoint lock if checkpoint_wait=0 for bulk curs…

…or open (#2897)

WT-2781 Add checkpoint_wait configuration for bulk cursor open API.

dist/api_data.py

@@ -820,8 +820,9 @@ def __cmp__(self, other):
 
 'WT_SESSION.drop' : Method([
     Config('checkpoint_wait', 'true', r'''
-        wait for the checkpoint lock, if \c checkpoint_wait=false, fail if
-        this lock is not available immediately''',
+        wait for the checkpoint lock, if \c checkpoint_wait=false, perform
+        the drop operation without taking a lock, returning EBUSY if the
+        operation conflicts with a running checkpoint''',
         type='boolean', undoc=True),
     Config('force', 'false', r'''
         return success if the object does not exist''',
@@ -902,6 +903,11 @@ def __cmp__(self, other):
         "WiredTigerCheckpoint" opens the most recent internal
         checkpoint taken for the object).  The cursor does not
         support data modification'''),
+    Config('checkpoint_wait', 'true', r'''
+        wait for the checkpoint lock, if \c checkpoint_wait=false, open the
+        cursor without taking a lock, returning EBUSY if the operation
+        conflicts with a running checkpoint''',
+        type='boolean', undoc=True),
     Config('dump', '', r'''
         configure the cursor for dump format inputs and outputs: "hex"
         selects a simple hexadecimal format, "json" selects a JSON format

src/config/config_def.c

@@ -317,6 +317,7 @@ static const WT_CONFIG_CHECK confchk_WT_SESSION_open_cursor[] = {
 	{ "append", "boolean", NULL, NULL, NULL, 0 },
 	{ "bulk", "string", NULL, NULL, NULL, 0 },
 	{ "checkpoint", "string", NULL, NULL, NULL, 0 },
+	{ "checkpoint_wait", "boolean", NULL, NULL, NULL, 0 },
 	{ "dump", "string",
 	    NULL, "choices=[\"hex\",\"json\",\"print\"]",
 	    NULL, 0 },
@@ -1066,10 +1067,10 @@ static const WT_CONFIG_ENTRY config_entries[] = {
 	  NULL, 0
 	},
 	{ "WT_SESSION.open_cursor",
-	  "append=0,bulk=0,checkpoint=,dump=,next_random=0,"
-	  "next_random_sample_size=0,overwrite=,raw=0,readonly=0,"
+	  "append=0,bulk=0,checkpoint=,checkpoint_wait=,dump=,next_random=0"
+	  ",next_random_sample_size=0,overwrite=,raw=0,readonly=0,"
 	  "skip_sort_check=0,statistics=,target=",
-	  confchk_WT_SESSION_open_cursor, 12
+	  confchk_WT_SESSION_open_cursor, 13
 	},
 	{ "WT_SESSION.rebalance",
 	  "",

src/cursor/cur_file.c

@@ -510,9 +510,10 @@ __wt_curfile_open(WT_SESSION_IMPL *session, const char *uri,
 	WT_CONFIG_ITEM cval;
 	WT_DECL_RET;
 	uint32_t flags;
-	bool bitmap, bulk;
+	bool bitmap, bulk, checkpoint_wait;
 
 	bitmap = bulk = false;
+	checkpoint_wait = true;
 	flags = 0;
 
 	/*
@@ -538,6 +539,12 @@ __wt_curfile_open(WT_SESSION_IMPL *session, const char *uri,
 		else if (!WT_STRING_MATCH("unordered", cval.str, cval.len))
 			WT_RET_MSG(session, EINVAL,
 			    "Value for 'bulk' must be a boolean or 'bitmap'");
+
+		if (bulk) {
+			WT_RET(__wt_config_gets(session,
+			    cfg, "checkpoint_wait", &cval));
+			checkpoint_wait = cval.val != 0;
+		}
 	}
 
 	/* Bulk handles require exclusive access. */
@@ -547,11 +554,11 @@ __wt_curfile_open(WT_SESSION_IMPL *session, const char *uri,
 	/* Get the handle and lock it while the cursor is using it. */
 	if (WT_PREFIX_MATCH(uri, "file:")) {
 		/*
-		 * If we are opening exclusive, get the handle while holding
-		 * the checkpoint lock.  This prevents a bulk cursor open
-		 * failing with EBUSY due to a database-wide checkpoint.
+		 * If we are opening exclusive and don't want a bulk cursor
+		 * open to fail with EBUSY due to a database-wide checkpoint,
+		 * get the handle while holding the checkpoint lock.
 		 */
-		if (LF_ISSET(WT_DHANDLE_EXCLUSIVE))
+		if (LF_ISSET(WT_DHANDLE_EXCLUSIVE) && checkpoint_wait)
 			WT_WITH_CHECKPOINT_LOCK(session, ret,
 			    ret = __wt_session_get_btree_ckpt(
 			    session, uri, cfg, flags));

src/session/session_api.c

@@ -733,8 +733,8 @@ __wt_session_drop(WT_SESSION_IMPL *session, const char *uri, const char *cfg[])
 		F_SET(session, WT_SESSION_LOCK_NO_WAIT);
 
 	/*
-	 * The checkpoint lock only is needed to avoid a spurious EBUSY error
-	 * return.
+	 * Take the checkpoint lock if there is a need to prevent the drop
+	 * operation from failing with EBUSY due to an ongoing checkpoint.
 	 */
 	if (checkpoint_wait)
 		WT_WITH_CHECKPOINT_LOCK(session, ret,