add lib/pq

vendor/github.com/lib/pq/internal/pqtime/loc.go

@@ -0,0 +1,37 @@
+package pqtime
+
+import (
+	"sync"
+	"time"
+)
+
+// The location cache caches the time zones typically used by the client.
+type locationCache struct {
+	cache map[int]*time.Location
+	lock  sync.Mutex
+}
+
+// All connections share the same list of timezones. Benchmarking shows that
+// about 5% speed could be gained by putting the cache in the connection and
+// losing the mutex, at the cost of a small amount of memory and a somewhat
+// significant increase in code complexity.
+var globalLocationCache = &locationCache{cache: make(map[int]*time.Location)}
+
+func Reset() {
+	globalLocationCache = &locationCache{cache: make(map[int]*time.Location)}
+}
+
+// Returns the cached timezone for the specified offset, creating and caching
+// it if necessary.
+func (c *locationCache) getLocation(offset int) *time.Location {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+	l, ok := c.cache[offset]
+	if !ok {
+		// TODO(v2): for offset=0 it should use some descriptive text like
+		// "without time zone".
+		l = time.FixedZone("", offset)
+		c.cache[offset] = l
+	}
+	return l
+}