note_other.go

     1  // Copyright 2024 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build !js
     6  
     7  package runtime
     8  
     9  // sleep and wakeup on one-time events.
    10  // before any calls to notesleep or notewakeup,
    11  // must call noteclear to initialize the Note.
    12  // then, exactly one thread can call notesleep
    13  // and exactly one thread can call notewakeup (once).
    14  // once notewakeup has been called, the notesleep
    15  // will return.  future notesleep will return immediately.
    16  // subsequent noteclear must be called only after
    17  // previous notesleep has returned, e.g. it's disallowed
    18  // to call noteclear straight after notewakeup.
    19  //
    20  // notetsleep is like notesleep but wakes up after
    21  // a given number of nanoseconds even if the event
    22  // has not yet happened.  if a goroutine uses notetsleep to
    23  // wake up early, it must wait to call noteclear until it
    24  // can be sure that no other goroutine is calling
    25  // notewakeup.
    26  //
    27  // notesleep/notetsleep are generally called on g0,
    28  // notetsleepg is similar to notetsleep but is called on user g.
    29  type note struct {
    30  	// Futex-based impl treats it as uint32 key,
    31  	// while sema-based impl as M* waitm.
    32  	key uintptr
    33  }
    34
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