hooks.go

     1  // Copyright 2022 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  package cfile
     6  
     7  import "internal/runtime/exithook"
     8  
     9  // InitHook is invoked from the main package "init" routine in
    10  // programs built with "-cover". This function is intended to be
    11  // called only by the compiler (via runtime/coverage.initHook).
    12  //
    13  // If 'istest' is false, it indicates we're building a regular program
    14  // ("go build -cover ..."), in which case we immediately try to write
    15  // out the meta-data file, and register emitCounterData as an exit
    16  // hook.
    17  //
    18  // If 'istest' is true (indicating that the program in question is a
    19  // Go test binary), then we tentatively queue up both emitMetaData and
    20  // emitCounterData as exit hooks. In the normal case (e.g. regular "go
    21  // test -cover" run) the testmain.go boilerplate will run at the end
    22  // of the test, write out the coverage percentage, and then invoke
    23  // MarkProfileEmitted to indicate that no more work needs to be
    24  // done. If however that call is never made, this is a sign that the
    25  // test binary is being used as a replacement binary for the tool
    26  // being tested, hence we do want to run exit hooks when the program
    27  // terminates.
    28  func InitHook(istest bool) {
    29  	// Note: hooks are run in reverse registration order, so
    30  	// register the counter data hook before the meta-data hook
    31  	// (in the case where two hooks are needed).
    32  	exithook.Add(exithook.Hook{F: emitCounterData, RunOnFailure: true})
    33  	if istest {
    34  		exithook.Add(exithook.Hook{F: emitMetaData, RunOnFailure: true})
    35  	} else {
    36  		emitMetaData()
    37  	}
    38  }
    39
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