-index
enable identifier and full text search index
(no search box is shown if -index is not set)
+ -index_throttle=0.75
+ index throttle value; a value of 0 means no time is allocated
+ to the indexer (the indexer will never finish), a value of 1.0
+ means that index creation is running at full throttle (other
+ goroutines may get no time while the index is built)
-maxresults=10000
maximum number of full text search results shown
(no full text index is built if maxresults <= 0)
templateDir = flag.String("templates", "", "directory containing alternate template files")
// search index
- indexEnabled = flag.Bool("index", false, "enable search index")
- maxResults = flag.Int("maxresults", 10000, "maximum number of full text search results shown")
+ indexEnabled = flag.Bool("index", false, "enable search index")
+ maxResults = flag.Int("maxresults", 10000, "maximum number of full text search results shown")
+ indexThrottle = flag.Float64("index_throttle", 0.75, "index throttle value; 0.0 = no time allocated, 1.0 = full throttle")
// file system mapping
fs FileSystem // the underlying file system for godoc
log.Printf("updating index...")
}
start := time.Nanoseconds()
- index := NewIndex(fsDirnames(), *maxResults > 0)
+ index := NewIndex(fsDirnames(), *maxResults > 0, *indexThrottle)
stop := time.Nanoseconds()
searchIndex.set(index)
if *verbose {
// NewIndex creates a new index for the .go files
// in the directories given by dirnames.
//
-func NewIndex(dirnames <-chan string, fulltextIndex bool) *Index {
+func NewIndex(dirnames <-chan string, fulltextIndex bool, throttle float64) *Index {
var x Indexer
+ th := NewThrottle(throttle, 0.1e9) // run at least 0.1s at a time
// initialize Indexer
x.fset = token.NewFileSet()
if !f.IsDirectory() {
x.visitFile(dirname, f, fulltextIndex)
}
+ th.Throttle()
}
}
Others: others,
}
wlist = append(wlist, &wordPair{canonical(w), w})
+ th.Throttle()
}
x.stats.Words = len(words)
--- /dev/null
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import "time"
+
+// A Throttle permits throttling of a goroutine by
+// calling the Throttle method repeatedly.
+//
+type Throttle struct {
+ f float64 // f = (1-r)/r for 0 < r < 1
+ tm int64 // minimum run time slice; >= 0
+ tr int64 // accumulated time running
+ ts int64 // accumulated time stopped
+ tt int64 // earliest throttle time (= time Throttle returned + tm)
+}
+
+// NewThrottle creates a new Throttle with a throttle value r and
+// a minimum allocated run time slice of tm nanoseconds:
+//
+// r == 0: "empty" throttle; the goroutine is always sleeping
+// r == 1: full throttle; the goroutine is never sleeping
+//
+// A value of r == 0.6 throttles a goroutine such that it runs
+// approx. 60% of the time, and sleeps approx. 40% of the time.
+// Values of r < 0 or r > 1 are clamped down to values between 0 and 1.
+// Values of tm < 0 are set to 0.
+//
+func NewThrottle(r float64, tm int64) *Throttle {
+ var f float64
+ switch {
+ case r <= 0:
+ f = -1 // indicates always sleep
+ case r >= 1:
+ f = 0 // assume r == 1 (never sleep)
+ default:
+ // 0 < r < 1
+ f = (1 - r) / r
+ }
+ if tm < 0 {
+ tm = 0
+ }
+ return &Throttle{f: f, tm: tm, tt: time.Nanoseconds() + tm}
+}
+
+// Throttle calls time.Sleep such that over time the ratio tr/ts between
+// accumulated run (tr) and sleep times (ts) approximates the value 1/(1-r)
+// where r is the throttle value. Throttle returns immediately (w/o sleeping)
+// if less than tm ns have passed since the last call to Throttle.
+//
+func (p *Throttle) Throttle() {
+ if p.f < 0 {
+ select {} // always sleep
+ }
+
+ t0 := time.Nanoseconds()
+ if t0 < p.tt {
+ return // keep running (minimum time slice not exhausted yet)
+ }
+
+ // accumulate running time
+ p.tr += t0 - (p.tt - p.tm)
+
+ // compute sleep time
+ // Over time we want:
+ //
+ // tr/ts = r/(1-r)
+ //
+ // Thus:
+ //
+ // ts = tr*f with f = (1-r)/r
+ //
+ // After some incremental run time δr added to the total run time
+ // tr, the incremental sleep-time δs to get to the same ratio again
+ // after waking up from time.Sleep is:
+ if δs := int64(float64(p.tr)*p.f) - p.ts; δs > 0 {
+ time.Sleep(δs)
+ }
+
+ // accumulate (actual) sleep time
+ t1 := time.Nanoseconds()
+ p.ts += t1 - t0
+
+ // set earliest next throttle time
+ p.tt = t1 + p.tm
+}