time: record monotonic clock reading in time.Now, for more accurate c…

…omparisons See https://golang.org/design/12914-monotonic for details. Fixes golang#12914. Change-Id: I80edc2e6c012b4ace7161c84cf067d444381a009 Reviewed-on: https://go-review.googlesource.com/36255 Run-TryBot: Russ Cox <rsc@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Caleb Spare <cespare@gmail.com> Reviewed-by: Ian Lance Taylor <iant@golang.org>
kmisha · Feb 3, 2017 · 0e33559 · 0e33559
1 parent 8179b9b
commit 0e33559
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Showing 43 changed files with 629 additions and 129 deletions.
diff --git a/src/archive/tar/tar_test.go b/src/archive/tar/tar_test.go
@@ -94,13 +94,16 @@ func TestRoundTrip(t *testing.T) {
 	var b bytes.Buffer
 	tw := NewWriter(&b)
 	hdr := &Header{
-		Name:    "file.txt",
-		Uid:     1 << 21, // too big for 8 octal digits
-		Size:    int64(len(data)),
-		ModTime: time.Now(),
+		Name: "file.txt",
+		Uid:  1 << 21, // too big for 8 octal digits
+		Size: int64(len(data)),
+		// AddDate to strip monotonic clock reading,
+		// and Round to discard sub-second precision,
+		// both of which are not included in the tar header
+		// and would otherwise break the round-trip check
+		// below.
+		ModTime: time.Now().AddDate(0, 0, 0).Round(1 * time.Second),
 	}
-	// tar only supports second precision.
-	hdr.ModTime = hdr.ModTime.Add(-time.Duration(hdr.ModTime.Nanosecond()) * time.Nanosecond)
 	if err := tw.WriteHeader(hdr); err != nil {
 		t.Fatalf("tw.WriteHeader: %v", err)
 	}

diff --git a/src/encoding/gob/gobencdec_test.go b/src/encoding/gob/gobencdec_test.go
@@ -746,7 +746,7 @@ func (i *isZeroBugInterface) GobDecode(data []byte) error {
 }
 
 func TestGobEncodeIsZero(t *testing.T) {
-	x := isZeroBug{time.Now(), "hello", -55, isZeroBugArray{1, 2}, isZeroBugInterface{}}
+	x := isZeroBug{time.Unix(1e9, 0), "hello", -55, isZeroBugArray{1, 2}, isZeroBugInterface{}}
 	b := new(bytes.Buffer)
 	enc := NewEncoder(b)
 	err := enc.Encode(x)

diff --git a/src/go/types/testdata/expr3.src b/src/go/types/testdata/expr3.src
@@ -207,7 +207,7 @@ func struct_literals() {
 	_ = time.Time{}
 	_ = time.Time{sec /* ERROR "unknown field" */ : 0}
 	_ = time.Time{
-		0 /* ERROR implicit assignment to unexported field sec in time.Time literal */,
+		0 /* ERROR implicit assignment to unexported field wall in time.Time literal */,
 		0 /* ERROR implicit assignment */ ,
 		nil /* ERROR implicit assignment */ ,
 	}

diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go
@@ -241,8 +241,7 @@ func stackBarrier()
 // in asm_*.s
 func return0()
 
-//go:linkname time_now time.now
-func time_now() (sec int64, nsec int32)
+func walltime() (sec int64, nsec int32)
 
 // in asm_*.s
 // not called directly; definitions here supply type information for traceback.
@@ -281,7 +280,7 @@ func prefetcht2(addr uintptr)
 func prefetchnta(addr uintptr)
 
 func unixnanotime() int64 {
-	sec, nsec := time_now()
+	sec, nsec := walltime()
 	return sec*1e9 + int64(nsec)
 }
 

diff --git a/src/runtime/sys_darwin_386.s b/src/runtime/sys_darwin_386.s
@@ -217,8 +217,8 @@ inreg:
 	ADCL	$0, DX
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$0
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$0
 	CALL	runtime·now(SB)
 	MOVL	$1000000000, CX
 	DIVL	CX

diff --git a/src/runtime/sys_darwin_amd64.s b/src/runtime/sys_darwin_amd64.s
@@ -198,8 +198,8 @@ TEXT runtime·nanotime(SB),NOSPLIT,$0-8
 	MOVQ	AX, ret+0(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$0-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$0-12
 	CALL	nanotime<>(SB)
 
 	// generated code for

diff --git a/src/runtime/sys_darwin_arm.s b/src/runtime/sys_darwin_arm.s
@@ -159,7 +159,7 @@ TEXT runtime·mincore(SB),NOSPLIT,$0
 	MOVW	R0, ret+12(FP)
 	RET
 
-TEXT time·now(SB), 7, $32
+TEXT runtime·walltime(SB), 7, $32
 	MOVW	$8(R13), R0  // timeval
 	MOVW	$0, R1  // zone
 	MOVW	$0, R2	// see issue 16570

diff --git a/src/runtime/sys_darwin_arm64.s b/src/runtime/sys_darwin_arm64.s
@@ -151,7 +151,7 @@ TEXT runtime·setitimer(SB),NOSPLIT,$0
 	SVC	$0x80
 	RET
 
-TEXT time·now(SB),NOSPLIT,$40-12
+TEXT runtime·walltime(SB),NOSPLIT,$40-12
 	MOVD	RSP, R0	// timeval
 	MOVD	R0, R9	// this is how dyld calls gettimeofday
 	MOVW	$0, R1	// zone

diff --git a/src/runtime/sys_dragonfly_amd64.s b/src/runtime/sys_dragonfly_amd64.s
@@ -148,8 +148,8 @@ TEXT runtime·setitimer(SB), NOSPLIT, $-8
 	SYSCALL
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVL	$232, AX // clock_gettime
 	MOVQ	$0, DI  	// CLOCK_REALTIME
 	LEAQ	8(SP), SI

diff --git a/src/runtime/sys_freebsd_386.s b/src/runtime/sys_freebsd_386.s
@@ -159,8 +159,8 @@ TEXT runtime·setitimer(SB), NOSPLIT, $-4
 	INT	$0x80
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVL	$232, AX // clock_gettime
 	LEAL	12(SP), BX
 	MOVL	$0, 4(SP)	// CLOCK_REALTIME

diff --git a/src/runtime/sys_freebsd_amd64.s b/src/runtime/sys_freebsd_amd64.s
@@ -142,8 +142,8 @@ TEXT runtime·setitimer(SB), NOSPLIT, $-8
 	SYSCALL
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVL	$232, AX // clock_gettime
 	MOVQ	$0, DI		// CLOCK_REALTIME
 	LEAQ	8(SP), SI

diff --git a/src/runtime/sys_freebsd_arm.s b/src/runtime/sys_freebsd_arm.s
@@ -166,8 +166,8 @@ TEXT runtime·setitimer(SB), NOSPLIT, $-8
 	SWI $0
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVW $0, R0 // CLOCK_REALTIME
 	MOVW $8(R13), R1
 	MOVW $SYS_clock_gettime, R7

diff --git a/src/runtime/sys_linux_386.s b/src/runtime/sys_linux_386.s
@@ -151,8 +151,8 @@ TEXT runtime·mincore(SB),NOSPLIT,$0-16
 	MOVL	AX, ret+12(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVL	$265, AX			// syscall - clock_gettime
 	MOVL	$0, BX		// CLOCK_REALTIME
 	LEAL	8(SP), CX

diff --git a/src/runtime/sys_linux_amd64.s b/src/runtime/sys_linux_amd64.s
@@ -135,8 +135,8 @@ TEXT runtime·mincore(SB),NOSPLIT,$0-28
 	MOVL	AX, ret+24(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$16
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$16
 	// Be careful. We're calling a function with gcc calling convention here.
 	// We're guaranteed 128 bytes on entry, and we've taken 16, and the
 	// call uses another 8.

diff --git a/src/runtime/sys_linux_arm.s b/src/runtime/sys_linux_arm.s
@@ -197,7 +197,7 @@ TEXT runtime·mincore(SB),NOSPLIT,$0
 	MOVW	R0, ret+12(FP)
 	RET
 
-TEXT time·now(SB), NOSPLIT, $32
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVW	$0, R0  // CLOCK_REALTIME
 	MOVW	$8(R13), R1  // timespec
 	MOVW	$SYS_clock_gettime, R7

diff --git a/src/runtime/sys_linux_arm64.s b/src/runtime/sys_linux_arm64.s
@@ -182,8 +182,8 @@ TEXT runtime·mincore(SB),NOSPLIT,$-8-28
 	MOVW	R0, ret+24(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$24-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$24-12
 	MOVW	$0, R0 // CLOCK_REALTIME
 	MOVD	RSP, R1
 	MOVD	$SYS_clock_gettime, R8

diff --git a/src/runtime/sys_linux_mips64x.s b/src/runtime/sys_linux_mips64x.s
@@ -172,8 +172,8 @@ TEXT runtime·mincore(SB),NOSPLIT,$-8-28
 	MOVW	R2, ret+24(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$16
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$16
 	MOVW	$0, R4 // CLOCK_REALTIME
 	MOVV	$0(R29), R5
 	MOVV	$SYS_clock_gettime, R2

diff --git a/src/runtime/sys_linux_mipsx.s b/src/runtime/sys_linux_mipsx.s
@@ -175,8 +175,8 @@ TEXT runtime·mincore(SB),NOSPLIT,$0-16
 	MOVW	R2, ret+12(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$8-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$8-12
 	MOVW	$0, R4	// CLOCK_REALTIME
 	MOVW	$4(R29), R5
 	MOVW	$SYS_clock_gettime, R2

diff --git a/src/runtime/sys_linux_ppc64x.s b/src/runtime/sys_linux_ppc64x.s
@@ -157,8 +157,8 @@ TEXT runtime·mincore(SB),NOSPLIT|NOFRAME,$0-28
 	MOVW	R3, ret+24(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$16
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$16
 	MOVD	$0, R3 // CLOCK_REALTIME
 	MOVD	$0(R1), R4
 	SYSCALL	$SYS_clock_gettime

diff --git a/src/runtime/sys_linux_s390x.s b/src/runtime/sys_linux_s390x.s
@@ -169,8 +169,8 @@ TEXT runtime·mincore(SB),NOSPLIT|NOFRAME,$0-28
 	MOVW	R2, ret+24(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$16
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$16
 	MOVW	$0, R2 // CLOCK_REALTIME
 	MOVD	$tp-16(SP), R3
 	MOVW	$SYS_clock_gettime, R1

diff --git a/src/runtime/sys_nacl_386.s b/src/runtime/sys_nacl_386.s
@@ -233,7 +233,7 @@ TEXT runtime·mmap(SB),NOSPLIT,$32
 	MOVL	AX, ret+24(FP)
 	RET
 
-TEXT time·now(SB),NOSPLIT,$20
+TEXT runtime·walltime(SB),NOSPLIT,$20
 	MOVL $0, 0(SP) // real time clock
 	LEAL 8(SP), AX
 	MOVL AX, 4(SP) // timespec
@@ -249,7 +249,7 @@ TEXT time·now(SB),NOSPLIT,$20
 	RET
 
 TEXT syscall·now(SB),NOSPLIT,$0
-	JMP time·now(SB)
+	JMP runtime·walltime(SB)
 
 TEXT runtime·nacl_clock_gettime(SB),NOSPLIT,$8
 	MOVL arg1+0(FP), AX

diff --git a/src/runtime/sys_nacl_amd64p32.s b/src/runtime/sys_nacl_amd64p32.s
@@ -242,7 +242,7 @@ TEXT runtime·mmap(SB),NOSPLIT,$8
 	MOVL	AX, ret+24(FP)
 	RET
 
-TEXT time·now(SB),NOSPLIT,$16
+TEXT runtime·walltime(SB),NOSPLIT,$16
 	MOVQ runtime·faketime(SB), AX
 	CMPQ AX, $0
 	JEQ realtime
@@ -268,7 +268,7 @@ realtime:
 	RET
 
 TEXT syscall·now(SB),NOSPLIT,$0
-	JMP time·now(SB)
+	JMP runtime·walltime(SB)
 
 TEXT runtime·nacl_clock_gettime(SB),NOSPLIT,$0
 	MOVL arg1+0(FP), DI

diff --git a/src/runtime/sys_nacl_arm.s b/src/runtime/sys_nacl_arm.s
@@ -196,7 +196,7 @@ TEXT runtime·mmap(SB),NOSPLIT,$8
 	MOVW	R0, ret+24(FP)
 	RET
 
-TEXT time·now(SB),NOSPLIT,$16
+TEXT runtime·walltime(SB),NOSPLIT,$16
 	MOVW	$0, R0 // real time clock
 	MOVW	$4(R13), R1
 	NACL_SYSCALL(SYS_clock_gettime)
@@ -209,7 +209,7 @@ TEXT time·now(SB),NOSPLIT,$16
 	RET
 
 TEXT syscall·now(SB),NOSPLIT,$0
-	B time·now(SB)
+	B runtime·walltime(SB)
 
 TEXT runtime·nacl_clock_gettime(SB),NOSPLIT,$0
 	MOVW	arg1+0(FP), R0

diff --git a/src/runtime/sys_netbsd_386.s b/src/runtime/sys_netbsd_386.s
@@ -134,8 +134,8 @@ TEXT runtime·setitimer(SB),NOSPLIT,$-4
 	INT	$0x80
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	LEAL	12(SP), BX
 	MOVL	$0, 4(SP)		// arg 1 - clock_id
 	MOVL	BX, 8(SP)		// arg 2 - tp

diff --git a/src/runtime/sys_netbsd_amd64.s b/src/runtime/sys_netbsd_amd64.s
@@ -169,8 +169,8 @@ TEXT runtime·setitimer(SB),NOSPLIT,$-8
 	SYSCALL
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVQ	$0, DI			// arg 1 - clock_id
 	LEAQ	8(SP), SI		// arg 2 - tp
 	MOVL	$427, AX		// sys_clock_gettime

diff --git a/src/runtime/sys_netbsd_arm.s b/src/runtime/sys_netbsd_arm.s
@@ -137,8 +137,8 @@ TEXT runtime·setitimer(SB),NOSPLIT,$-4
 	SWI $0xa001a9	// sys_setitimer
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVW $0, R0	// CLOCK_REALTIME
 	MOVW $8(R13), R1
 	SWI $0xa001ab	// clock_gettime

diff --git a/src/runtime/sys_openbsd_386.s b/src/runtime/sys_openbsd_386.s
@@ -140,8 +140,8 @@ TEXT runtime·setitimer(SB),NOSPLIT,$-4
 	INT	$0x80
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	LEAL	12(SP), BX
 	MOVL	$0, 4(SP)		// arg 1 - clock_id
 	MOVL	BX, 8(SP)		// arg 2 - tp

diff --git a/src/runtime/sys_openbsd_amd64.s b/src/runtime/sys_openbsd_amd64.s
@@ -180,8 +180,8 @@ TEXT runtime·setitimer(SB),NOSPLIT,$-8
 	SYSCALL
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVQ	$0, DI			// arg 1 - clock_id
 	LEAQ	8(SP), SI		// arg 2 - tp
 	MOVL	$87, AX			// sys_clock_gettime

diff --git a/src/runtime/sys_openbsd_arm.s b/src/runtime/sys_openbsd_arm.s
@@ -150,8 +150,8 @@ TEXT runtime·setitimer(SB),NOSPLIT,$0
 	SWI	$0
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB), NOSPLIT, $32
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB), NOSPLIT, $32
 	MOVW	CLOCK_REALTIME, R0	// arg 1 - clock_id
 	MOVW	$8(R13), R1		// arg 2 - tp
 	MOVW	$87, R12		// sys_clock_gettime

diff --git a/src/runtime/sys_plan9_386.s b/src/runtime/sys_plan9_386.s
@@ -102,8 +102,8 @@ TEXT runtime·nsec(SB),NOSPLIT,$8
 	MOVL	$-1, ret_hi+8(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$8-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$8-12
 	CALL	runtime·nanotime(SB)
 	MOVL	0(SP), AX
 	MOVL	4(SP), DX

diff --git a/src/runtime/sys_plan9_amd64.s b/src/runtime/sys_plan9_amd64.s
@@ -92,8 +92,8 @@ TEXT runtime·nsec(SB),NOSPLIT,$0
 	MOVQ	AX, ret+8(FP)
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$8-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$8-12
 	CALL	runtime·nanotime(SB)
 	MOVQ	0(SP), AX
 

diff --git a/src/runtime/sys_plan9_arm.s b/src/runtime/sys_plan9_arm.s
@@ -139,7 +139,7 @@ TEXT runtime·nsec(SB),NOSPLIT,$-4-12
 	RET
 
 // time.now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$12-12
+TEXT runtime·walltime(SB),NOSPLIT,$12-12
 	// use nsec system call to get current time in nanoseconds
 	MOVW	$sysnsec_lo-8(SP), R0	// destination addr
 	MOVW	R0,res-12(SP)

diff --git a/src/runtime/sys_solaris_amd64.s b/src/runtime/sys_solaris_amd64.s
@@ -354,8 +354,8 @@ TEXT runtime·osyield1(SB),NOSPLIT,$0
 	CALL	AX
 	RET
 
-// func now() (sec int64, nsec int32)
-TEXT time·now(SB),NOSPLIT,$8-12
+// func walltime() (sec int64, nsec int32)
+TEXT runtime·walltime(SB),NOSPLIT,$8-12
 	CALL	runtime·nanotime(SB)
 	MOVQ	0(SP), AX