mirror of
https://github.com/neilotoole/sq.git
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138 lines
2.7 KiB
Go
138 lines
2.7 KiB
Go
// Package cleanup provides functionality for executing
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// cleanup functions.
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package cleanup
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import (
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"io"
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"sync"
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"github.com/neilotoole/sq/libsq/core/errz"
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)
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// Nop is a no-op cleanup.Func.
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var Nop = func() error { return nil }
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// New returns a new Cleanup instance.
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func New() *Cleanup {
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return &Cleanup{}
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}
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// Cleanup encapsulates a slice of cleanup funcs. The
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// funcs are executed by Run in reverse order to which
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// they are added.
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// Cleanup is safe for concurrent use.
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type Cleanup struct {
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fns []func() error
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mu sync.Mutex
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}
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// Len returns the count of cleanup funcs.
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func (cu *Cleanup) Len() int {
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if cu == nil {
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return 0
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}
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cu.mu.Lock()
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defer cu.mu.Unlock()
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return len(cu.fns)
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}
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// Append c's cleanup funcs to cu.
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func (cu *Cleanup) Append(c *Cleanup) *Cleanup {
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if c == nil || c == cu {
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return cu
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}
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c.mu.Lock()
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defer c.mu.Unlock()
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cu.mu.Lock()
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defer cu.mu.Unlock()
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cu.fns = append(cu.fns, c.fns...)
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return cu
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}
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// Add adds a cleanup func.
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func (cu *Cleanup) Add(fn func()) *Cleanup {
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if fn == nil {
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// For convenience in avoiding boilerplate nil checks
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// in the caller, we just ignore the nil arg.
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return cu
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}
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cu.mu.Lock()
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defer cu.mu.Unlock()
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cu.fns = append(cu.fns, func() error {
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fn()
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return nil
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})
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return cu
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}
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// AddE adds an error-returning cleanup func.
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func (cu *Cleanup) AddE(fn func() error) *Cleanup {
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if fn == nil {
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// For convenience in avoiding boilerplate nil checks
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// in the caller, we just ignore the nil arg.
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return cu
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}
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cu.mu.Lock()
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defer cu.mu.Unlock()
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cu.fns = append(cu.fns, fn)
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return cu
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}
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// AddC adds c.Close as a cleanup func. This method
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// is no-op if c is nil.
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func (cu *Cleanup) AddC(c io.Closer) *Cleanup {
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if c == nil {
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// For convenience in avoiding boilerplate nil checks
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// in the caller, we just ignore the nil arg.
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return cu
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}
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cu.mu.Lock()
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defer cu.mu.Unlock()
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cu.fns = append(cu.fns, c.Close)
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return cu
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}
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// Run executes the cleanup funcs in reverse order to which
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// they were added. All funcs are executed, even in the presence of
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// an error from a func. Any errors are combined into a single error.
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// The set of cleanup funcs is removed when Run returns.
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//
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// TODO: Consider renaming Run to Close so that Cleanup
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// implements io.Closer?
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func (cu *Cleanup) Run() error {
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if cu == nil {
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return nil
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}
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cu.mu.Lock()
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defer cu.mu.Unlock()
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if len(cu.fns) == 0 {
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return nil
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}
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// Capture any cleanup func errors
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var err error
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// Run cleanups in reverse order
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for i := len(cu.fns) - 1; i >= 0; i-- {
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fn := cu.fns[i]
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if fn == nil {
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// skip any nil fns
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continue
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}
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err = errz.Append(err, fn())
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}
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// Set fns to nil so that the cleanup funcs
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// can't get run twice.
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cu.fns = nil
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return err
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}
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