From d41316bc0ff5738e5108b6ed057a2dd82804a054 Mon Sep 17 00:00:00 2001
From: Dhruba Borthakur <dhruba@dev3936.snc6.facebook.com>
Date: Sat, 18 Aug 2012 00:26:50 -0700
Subject: [PATCH] Prevent concurrent multiple opens of leveldb database.

Summary:
The fcntl call cannot detect lock conflicts when invoked multiple times
from the same thread.
Use a static lockedFile Set to record the paths that are locked.
A lockfile request checks to see if htis filename already exists in
lockedFiles, if so, then it triggers an error. Otherwise, it inserts
the filename in the lockedFiles Set.
A unlock file request verifies that the filename is in the lockedFiles
set and removes it from lockedFiles set.

Test Plan: unit test attached

Reviewers: heyongqiang

Reviewed By: heyongqiang

Differential Revision: https://reviews.facebook.net/D4755
---
 Makefile | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 1635566ad..d8c3f0ce9 100644
--- a/Makefile
+++ b/Makefile
@@ -56,7 +56,6 @@ TESTS = \
 	write_batch_test \
 	filelock_test
 
-
 TOOLS = \
 	manifest_dump \
 	leveldb_shell \
@@ -198,6 +197,10 @@ sst_dump: tools/sst_dump.o $(LIBOBJECTS)
 $(VERSIONFILE):	build_detect_version
 	$(shell ./build_detect_platform build_config.mk)
 
+filelock_test: util/filelock_test.o $(LIBOBJECTS) $(TESTHARNESS)
+	$(CXX) util/filelock_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+
+
 ifeq ($(PLATFORM), IOS)
 # For iOS, create universal object files to be used on both the simulator and
 # a device.