[experiment] add alternative wasm sqlite3 implementation available via build-tag (#2863)

This allows for building GoToSocial with [SQLite transpiled to WASM](https://github.com/ncruces/go-sqlite3) and accessed through [Wazero](https://wazero.io/).

1 files changed, 76 insertions, 0 deletions

diff --git a/vendor/github.com/tetratelabs/wazero/internal/platform/time.go b/vendor/github.com/tetratelabs/wazero/internal/platform/time.go
new file mode 100644
index 000000000..fa9da1acb
--- /dev/null
+++ b/vendor/github.com/tetratelabs/wazero/internal/platform/time.go
@@ -0,0 +1,76 @@
+package platform
+
+import (
+	"sync/atomic"
+	"time"
+
+	"github.com/tetratelabs/wazero/sys"
+)
+
+const (
+	ms = int64(time.Millisecond)
+	// FakeEpochNanos is midnight UTC 2022-01-01 and exposed for testing
+	FakeEpochNanos = 1640995200000 * ms
+)
+
+// NewFakeWalltime implements sys.Walltime with FakeEpochNanos that increases by 1ms each reading.
+// See /RATIONALE.md
+func NewFakeWalltime() sys.Walltime {
+	// AddInt64 returns the new value. Adjust so the first reading will be FakeEpochNanos
+	t := FakeEpochNanos - ms
+	return func() (sec int64, nsec int32) {
+		wt := atomic.AddInt64(&t, ms)
+		return wt / 1e9, int32(wt % 1e9)
+	}
+}
+
+// NewFakeNanotime implements sys.Nanotime that increases by 1ms each reading.
+// See /RATIONALE.md
+func NewFakeNanotime() sys.Nanotime {
+	// AddInt64 returns the new value. Adjust so the first reading will be zero.
+	t := int64(0) - ms
+	return func() int64 {
+		return atomic.AddInt64(&t, ms)
+	}
+}
+
+// FakeNanosleep implements sys.Nanosleep by returning without sleeping.
+var FakeNanosleep = sys.Nanosleep(func(int64) {})
+
+// FakeOsyield implements sys.Osyield by returning without yielding.
+var FakeOsyield = sys.Osyield(func() {})
+
+// Walltime implements sys.Walltime with time.Now.
+//
+// Note: This is only notably less efficient than it could be is reading
+// runtime.walltime(). time.Now defensively reads nanotime also, just in case
+// time.Since is used. This doubles the performance impact. However, wall time
+// is likely to be read less frequently than Nanotime. Also, doubling the cost
+// matters less on fast platforms that can return both in <=100ns.
+func Walltime() (sec int64, nsec int32) {
+	t := time.Now()
+	return t.Unix(), int32(t.Nanosecond())
+}
+
+// nanoBase uses time.Now to ensure a monotonic clock reading on all platforms
+// via time.Since.
+var nanoBase = time.Now()
+
+// nanotimePortable implements sys.Nanotime with time.Since.
+//
+// Note: This is less efficient than it could be is reading runtime.nanotime(),
+// Just to do that requires CGO.
+func nanotimePortable() int64 {
+	return time.Since(nanoBase).Nanoseconds()
+}
+
+// Nanotime implements sys.Nanotime with runtime.nanotime() if CGO is available
+// and time.Since if not.
+func Nanotime() int64 {
+	return nanotime()
+}
+
+// Nanosleep implements sys.Nanosleep with time.Sleep.
+func Nanosleep(ns int64) {
+	time.Sleep(time.Duration(ns))
+}