runtime: unify mutex code across OSes
The change introduces 2 generic mutex implementations
(futex- and semaphore-based). Each OS chooses a suitable mutex
implementation and implements few callbacks (e.g. futex wait/wake).
The CL reduces code duplication, extends some optimizations available
only on Linux/Windows to other OSes and provides ground
for futher optimizations. Chan finalizers are finally eliminated.
(Linux/amd64, 8 HT cores)
benchmark old new
BenchmarkChanContended 83.6 77.8 ns/op
BenchmarkChanContended-2 341 328 ns/op
BenchmarkChanContended-4 382 383 ns/op
BenchmarkChanContended-8 390 374 ns/op
BenchmarkChanContended-16 313 291 ns/op
(Darwin/amd64, 2 cores)
benchmark old new
BenchmarkChanContended 159 172 ns/op
BenchmarkChanContended-2 6735 263 ns/op
BenchmarkChanContended-4 10384 255 ns/op
BenchmarkChanCreation 1174 407 ns/op
BenchmarkChanCreation-2 4007 254 ns/op
BenchmarkChanCreation-4 4029 246 ns/op
R=rsc, jsing, hectorchu
CC=golang-dev
https://golang.org/cl/5140043
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index e45808f..685725a 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -47,14 +47,13 @@
typedef struct Func Func;
typedef struct G G;
typedef struct Gobuf Gobuf;
-typedef struct Lock Lock;
+typedef union Lock Lock;
typedef struct M M;
typedef struct Mem Mem;
typedef union Note Note;
typedef struct Slice Slice;
typedef struct Stktop Stktop;
typedef struct String String;
-typedef struct Usema Usema;
typedef struct SigTab SigTab;
typedef struct MCache MCache;
typedef struct FixAlloc FixAlloc;
@@ -117,32 +116,15 @@
/*
* structures
*/
-struct Lock
+union Lock
{
-#ifdef __WINDOWS__
- M* waitm; // linked list of waiting M's
-#else
- uint32 key;
- uint32 sema; // for OS X
-#endif
-};
-struct Usema
-{
- uint32 u;
- uint32 k;
+ uint32 key; // futex-based impl
+ M* waitm; // linked list of waiting M's (sema-based impl)
};
union Note
{
- struct { // Linux
- uint32 state;
- };
- struct { // Windows
- Lock lock;
- };
- struct { // OS X
- int32 wakeup;
- Usema sema;
- };
+ uint32 key; // futex-based impl
+ M* waitm; // waiting M (sema-based impl)
};
struct String
{
@@ -253,11 +235,13 @@
uint32 freglo[16]; // D[i] lsb and F[i]
uint32 freghi[16]; // D[i] msb and F[i+16]
uint32 fflag; // floating point compare flags
-
+ M* nextwaitm; // next M waiting for lock
+ uintptr waitsema; // semaphore for parking on locks
+ uint32 waitsemacount;
+ uint32 waitsemalock;
+
#ifdef __WINDOWS__
void* thread; // thread handle
- void* event; // event for signalling
- M* nextwaitm; // next M waiting for lock
#endif
uintptr end[];
};
@@ -409,7 +393,6 @@
int8* runtime·goos;
int32 runtime·ncpu;
extern bool runtime·iscgo;
-extern void (*runtime·destroylock)(Lock*);
/*
* common functions and data
