From 88d3eeb9508b21528279d5e2b4acd10399d47193 Mon Sep 17 00:00:00 2001
From: MITSUNARI Shigeo <herumi@nifty.com>
Date: Wed, 16 Aug 2017 06:10:20 +0900
Subject: blsInit is thread safe

---
 include/bls/bls.h      | 14 ++++++++------
 src/bls_c.cpp          | 24 ++++++++++++++++--------
 test/bls_c384_test.cpp |  7 ++++---
 3 files changed, 28 insertions(+), 17 deletions(-)

diff --git a/include/bls/bls.h b/include/bls/bls.h
index 2a9df84..6b4caa4 100644
--- a/include/bls/bls.h
+++ b/include/bls/bls.h
@@ -45,15 +45,17 @@ typedef struct {
 
 /*
 	initialize this library
-	call this once before using the other method
+	call this once before using the other functions
+	@param curve [in] enum value defined in mcl/bn.h
+	@param maxUnitSize [in] MCLBN_FP_UNIT_SIZE (fixed)
 	return 0 if success
-	@note init() is not thread safe
+	@note blsInit() is thread safe and serialized if it is called simultaneously
+	but don't call it while using other functions.
 */
 BLS_DLL_API int blsInit(int curve, int maxUnitSize);
-/*
-	wait for the finish of the first call blsInit() and do nothing
-*/
-BLS_DLL_API int blsInitThreadSafe(int curve, int maxUnitSize);
+
+// not thread safe version (old blsInit)
+BLS_DLL_API int blsInitNotThreadSafe(int curve, int maxUnitSize);
 
 BLS_DLL_API size_t blsGetOpUnitSize(void);
 // return strlen(buf) if success else 0
diff --git a/src/bls_c.cpp b/src/bls_c.cpp
index 563ecc9..72074fe 100644
--- a/src/bls_c.cpp
+++ b/src/bls_c.cpp
@@ -25,7 +25,7 @@ static std::vector<Fp6> g_Qcoeff; // precomputed Q
 static const G2& getQ() { return g_Q; }
 static const std::vector<Fp6>& getQcoeff() { return g_Qcoeff; }
 
-int blsInit(int curve, int maxUnitSize)
+int blsInitNotThreadSafe(int curve, int maxUnitSize)
 	try
 {
 	if (mclBn_init(curve, maxUnitSize) != 0) return -1;
@@ -36,22 +36,30 @@ int blsInit(int curve, int maxUnitSize)
 	return -1;
 }
 
-#if CYBOZU_CPP_VERSION >= CYBOZU_CPP_VERSION_CPP11
+#if defined(CYBOZU_CPP_VERSION) && CYBOZU_CPP_VERSION >= CYBOZU_CPP_VERSION_CPP11
 #include <mutex>
-static std::mutex g_mutex;
-static int g_curve = -1;
+	#define USE_STD_MUTEX
+#else
+#include <cybozu/mutex.hpp>
+#endif
 
-int blsInitThreadSafe(int curve, int maxUnitSize)
+int blsInit(int curve, int maxUnitSize)
 {
 	int ret = 0;
-	std::lock_guard<std::mutex> lock(g_mutex);
+#ifdef USE_STD_MUTEX
+	static std::mutex m;
+	std::lock_guard<std::mutex> lock(m);
+#else
+	static cybozu::Mutex m;
+	cybozu::AutoLock lock(m);
+#endif
+	static int g_curve = -1;
 	if (g_curve != curve) {
-		ret = blsInit(curve, maxUnitSize);
+		ret = blsInitNotThreadSafe(curve, maxUnitSize);
 		g_curve = curve;
 	}
 	return ret;
 }
-#endif
 
 static inline const mclBnG1 *cast(const G1* x) { return (const mclBnG1*)x; }
 static inline const mclBnG2 *cast(const G2* x) { return (const mclBnG2*)x; }
diff --git a/test/bls_c384_test.cpp b/test/bls_c384_test.cpp
index 2e61e2c..21612da 100644
--- a/test/bls_c384_test.cpp
+++ b/test/bls_c384_test.cpp
@@ -1,4 +1,5 @@
 #include <cybozu/test.hpp>
+#include <cybozu/inttype.hpp>
 #include <bls/bls.h>
 #include <string.h>
 
@@ -62,7 +63,7 @@ void blsOrderTest(const char *curveOrder, const char *fieldOrder)
 	CYBOZU_TEST_EQUAL(buf, fieldOrder);
 }
 
-#if CYBOZU_CPP_VERSION >= CYBOZU_CPP_VERSION_CPP11
+#if defined(CYBOZU_CPP_VERSION) && CYBOZU_CPP_VERSION >= CYBOZU_CPP_VERSION_CPP11
 #include <thread>
 #include <vector>
 struct Thread {
@@ -86,7 +87,7 @@ CYBOZU_TEST_AUTO(multipleInit)
 	{
 		std::vector<Thread> vt(n);
 		for (size_t i = 0; i < n; i++) {
-			vt[i].run(blsInitThreadSafe, mclBn_CurveFp254BNb, MCLBN_FP_UNIT_SIZE);
+			vt[i].run(blsInit, mclBn_CurveFp254BNb, MCLBN_FP_UNIT_SIZE);
 		}
 	}
 	CYBOZU_TEST_EQUAL(blsGetOpUnitSize(), 4u);
@@ -94,7 +95,7 @@ CYBOZU_TEST_AUTO(multipleInit)
 	{
 		std::vector<Thread> vt(n);
 		for (size_t i = 0; i < n; i++) {
-			vt[i].run(blsInitThreadSafe, mclBn_CurveFp382_1, MCLBN_FP_UNIT_SIZE);
+			vt[i].run(blsInit, mclBn_CurveFp382_1, MCLBN_FP_UNIT_SIZE);
 		}
 	}
 	CYBOZU_TEST_EQUAL(blsGetOpUnitSize(), 6u);
-- 
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