Remove CoarseTime

It is not clear why @valyala introduced this coarse time. Benchmarks on
different systems show that the speedup is no where enough to justify
the added code complexity and bugs it seems to have introduced.

Mac:
BenchmarkCoarseTimeNow-8   	2000000000	         2.49 ns/op
0 B/op	       0 allocs/op
BenchmarkTimeNow-8         	500000000	         3.14 ns/op
0 B/op	       0 allocs/op

Ubuntu:
BenchmarkCoarseTimeNow-4   	300000000	         6.74 ns/op
0 B/op	       0 allocs/op
BenchmarkTimeNow-4         	100000000	        15.9 ns/op
0 B/op	       0 allocs/op

This reverts commit erikdubbelboer@6309f42
and erikdubbelboer@32c72cd.

See: valyala#271,
valyala#269 and
valyala#261.

client.go

@@ -1041,7 +1041,7 @@ func (c *HostClient) doNonNilReqResp(req *Request, resp *Response) (bool, error)
 		panic("BUG: resp cannot be nil")
 	}
 
-	atomic.StoreUint32(&c.lastUseTime, uint32(CoarseTimeNow().Unix()-startTimeUnix))
+	atomic.StoreUint32(&c.lastUseTime, uint32(time.Now().Unix()-startTimeUnix))
 
 	// Free up resources occupied by response before sending the request,
 	// so the GC may reclaim these resources (e.g. response body).
@@ -1057,7 +1057,7 @@ func (c *HostClient) doNonNilReqResp(req *Request, resp *Response) (bool, error)
 		// Optimization: update write deadline only if more than 25%
 		// of the last write deadline exceeded.
 		// See https://github.com/golang/go/issues/15133 for details.
-		currentTime := CoarseTimeNow()
+		currentTime := time.Now()
 		if currentTime.Sub(cc.lastWriteDeadlineTime) > (c.WriteTimeout >> 2) {
 			if err = conn.SetWriteDeadline(currentTime.Add(c.WriteTimeout)); err != nil {
 				c.closeConn(cc)
@@ -1101,7 +1101,7 @@ func (c *HostClient) doNonNilReqResp(req *Request, resp *Response) (bool, error)
 		// Optimization: update read deadline only if more than 25%
 		// of the last read deadline exceeded.
 		// See https://github.com/golang/go/issues/15133 for details.
-		currentTime := CoarseTimeNow()
+		currentTime := time.Now()
 		if currentTime.Sub(cc.lastReadDeadlineTime) > (c.ReadTimeout >> 2) {
 			if err = conn.SetReadDeadline(currentTime.Add(c.ReadTimeout)); err != nil {
 				c.closeConn(cc)
@@ -1276,7 +1276,7 @@ func acquireClientConn(conn net.Conn) *clientConn {
 	}
 	cc := v.(*clientConn)
 	cc.c = conn
-	cc.createdTime = CoarseTimeNow()
+	cc.createdTime = time.Now()
 	return cc
 }
 
@@ -1288,7 +1288,7 @@ func releaseClientConn(cc *clientConn) {
 var clientConnPool sync.Pool
 
 func (c *HostClient) releaseConn(cc *clientConn) {
-	cc.lastUseTime = CoarseTimeNow()
+	cc.lastUseTime = time.Now()
 	c.connsLock.Lock()
 	c.conns = append(c.conns, cc)
 	c.connsLock.Unlock()
@@ -1991,7 +1991,7 @@ func (c *pipelineConnClient) writer(conn net.Conn, stopCh <-chan struct{}) error
 			// Optimization: update write deadline only if more than 25%
 			// of the last write deadline exceeded.
 			// See https://github.com/golang/go/issues/15133 for details.
-			currentTime := CoarseTimeNow()
+			currentTime := time.Now()
 			if currentTime.Sub(lastWriteDeadlineTime) > (writeTimeout >> 2) {
 				if err = conn.SetWriteDeadline(currentTime.Add(writeTimeout)); err != nil {
 					w.err = err
@@ -2072,7 +2072,7 @@ func (c *pipelineConnClient) reader(conn net.Conn, stopCh <-chan struct{}) error
 			// Optimization: update read deadline only if more than 25%
 			// of the last read deadline exceeded.
 			// See https://github.com/golang/go/issues/15133 for details.
-			currentTime := CoarseTimeNow()
+			currentTime := time.Now()
 			if currentTime.Sub(lastReadDeadlineTime) > (readTimeout >> 2) {
 				if err = conn.SetReadDeadline(currentTime.Add(readTimeout)); err != nil {
 					w.err = err

server.go

@@ -598,18 +598,13 @@ func (ctx *RequestCtx) ConnID() uint64 {
 	return ctx.connID
 }
 
-// Time returns RequestHandler call time truncated to the nearest second.
-//
-// Call time.Now() at the beginning of RequestHandler in order to obtain
-// precise RequestHandler call time.
+// Time returns RequestHandler call time.
 func (ctx *RequestCtx) Time() time.Time {
 	return ctx.time
 }
 
 // ConnTime returns the time server starts serving the connection
 // the current request came from.
-//
-// The returned time is truncated to the nearest second.
 func (ctx *RequestCtx) ConnTime() time.Time {
 	return ctx.connTime
 }
@@ -1319,7 +1314,7 @@ func (s *Server) Serve(ln net.Listener) error {
 			if time.Since(lastOverflowErrorTime) > time.Minute {
 				s.logger().Printf("The incoming connection cannot be served, because %d concurrent connections are served. "+
 					"Try increasing Server.Concurrency", maxWorkersCount)
-				lastOverflowErrorTime = CoarseTimeNow()
+				lastOverflowErrorTime = time.Now()
 			}
 
 			// The current server reached concurrency limit,
@@ -1361,7 +1356,7 @@ func acceptConn(s *Server, ln net.Listener, lastPerIPErrorTime *time.Time) (net.
 				if time.Since(*lastPerIPErrorTime) > time.Minute {
 					s.logger().Printf("The number of connections from %s exceeds MaxConnsPerIP=%d",
 						getConnIP4(c), s.MaxConnsPerIP)
-					*lastPerIPErrorTime = CoarseTimeNow()
+					*lastPerIPErrorTime = time.Now()
 				}
 				continue
 			}
@@ -1476,7 +1471,7 @@ func (s *Server) serveConn(c net.Conn) error {
 	serverName := s.getServerName()
 	connRequestNum := uint64(0)
 	connID := nextConnID()
-	currentTime := CoarseTimeNow()
+	currentTime := time.Now()
 	connTime := currentTime
 	maxRequestBodySize := s.MaxRequestBodySize
 	if maxRequestBodySize <= 0 {
@@ -1533,7 +1528,7 @@ func (s *Server) serveConn(c net.Conn) error {
 			}
 		}
 
-		currentTime = CoarseTimeNow()
+		currentTime = time.Now()
 		ctx.lastReadDuration = currentTime.Sub(ctx.time)
 
 		if err != nil {
@@ -1674,7 +1669,7 @@ func (s *Server) serveConn(c net.Conn) error {
 			break
 		}
 
-		currentTime = CoarseTimeNow()
+		currentTime = time.Now()
 	}
 
 	if br != nil {
@@ -1730,7 +1725,7 @@ func (s *Server) updateWriteDeadline(c net.Conn, ctx *RequestCtx, lastDeadlineTi
 	// Optimization: update write deadline only if more than 25%
 	// of the last write deadline exceeded.
 	// See https://github.com/golang/go/issues/15133 for details.
-	currentTime := CoarseTimeNow()
+	currentTime := time.Now()
 	if currentTime.Sub(lastDeadlineTime) > (writeTimeout >> 2) {
 		if err := c.SetWriteDeadline(currentTime.Add(writeTimeout)); err != nil {
 			panic(fmt.Sprintf("BUG: error in SetWriteDeadline(%s): %s", writeTimeout, err))
@@ -1913,7 +1908,7 @@ func (ctx *RequestCtx) Init2(conn net.Conn, logger Logger, reduceMemoryUsage boo
 	ctx.connID = nextConnID()
 	ctx.s = fakeServer
 	ctx.connRequestNum = 0
-	ctx.connTime = CoarseTimeNow()
+	ctx.connTime = time.Now()
 	ctx.time = ctx.connTime
 
 	keepBodyBuffer := !reduceMemoryUsage

workerpool.go

@@ -187,7 +187,7 @@ func (wp *workerPool) getCh() *workerChan {
 }
 
 func (wp *workerPool) release(ch *workerChan) bool {
-	ch.lastUseTime = CoarseTimeNow()
+	ch.lastUseTime = time.Now()
 	wp.lock.Lock()
 	if wp.mustStop {
 		wp.lock.Unlock()