github.com/gdamore/mangos@v1.4.0/util.go (about)

     1  // Copyright 2015 The Mangos Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use file except in compliance with the License.
     5  // You may obtain a copy of the license at
     6  //
     7  //    http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package mangos
    16  
    17  import (
    18  	"fmt"
    19  	"runtime"
    20  	"strings"
    21  	"time"
    22  )
    23  
    24  // mkTimer creates a timer based upon a duration.  If however
    25  // a zero valued duration is passed, then a nil channel is passed
    26  // i.e. never selectable.  This allows the output to be readily used
    27  // with deadlines in network connections, etc.
    28  func mkTimer(deadline time.Duration) <-chan time.Time {
    29  
    30  	if deadline == 0 {
    31  		return nil
    32  	}
    33  
    34  	return time.After(deadline)
    35  }
    36  
    37  var debug = true
    38  
    39  func debugf(format string, args ...interface{}) {
    40  	if debug {
    41  		_, file, line, ok := runtime.Caller(1)
    42  		if !ok {
    43  			file = "<?>"
    44  			line = 0
    45  		} else {
    46  			if i := strings.LastIndex(file, "/"); i >= 0 {
    47  				file = file[i+1:]
    48  			}
    49  		}
    50  		fmt.Printf("DEBUG: %s:%d [%s]: %s\n", file, line,
    51  			time.Now().String(), fmt.Sprintf(format, args...))
    52  	}
    53  }
    54  
    55  // DrainChannel waits for the channel of Messages to finish
    56  // emptying (draining) for up to the expiration.  It returns
    57  // true if the drain completed (the channel is empty), false otherwise.
    58  func DrainChannel(ch chan<- *Message, expire time.Time) bool {
    59  	var dur = time.Millisecond * 10
    60  
    61  	for {
    62  		if len(ch) == 0 {
    63  			return true
    64  		}
    65  		now := time.Now()
    66  		if now.After(expire) {
    67  			return false
    68  		}
    69  		// We sleep the lesser of the remaining time, or
    70  		// 10 milliseconds.  This polling is kind of suboptimal for
    71  		// draining, but its far far less complicated than trying to
    72  		// arrange special messages to force notification, etc.
    73  		dur = expire.Sub(now)
    74  		if dur > time.Millisecond*10 {
    75  			dur = time.Millisecond * 10
    76  		}
    77  		time.Sleep(dur)
    78  	}
    79  }