mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-11-23 04:06:39 +00:00
131 lines
3.1 KiB
Go
131 lines
3.1 KiB
Go
package runners
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import (
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"context"
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"errors"
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"fmt"
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"sync"
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"time"
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)
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// FuncRunner provides a means of managing long-running functions e.g. main logic loops.
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type FuncRunner struct {
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// HandOff is the time after which a blocking function will be considered handed off
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HandOff time.Duration
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// ErrorHandler is the function that errors are passed to when encountered by the
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// provided function. This can be used both for logging, and for error filtering
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ErrorHandler func(err error) error
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svc Service // underlying service to manage start/stop
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err error // last-set error
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mu sync.Mutex // protects err
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}
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// Go will attempt to run 'fn' asynchronously. The provided context is used to propagate requested
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// cancel if FuncRunner.Stop() is called. Any returned error will be passed to FuncRunner.ErrorHandler
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// for filtering/logging/etc. Any blocking functions will be waited on for FuncRunner.HandOff amount of
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// time before considering the function as handed off. Returned bool is success state, i.e. returns true
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// if function is successfully handed off or returns within hand off time with nil error.
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func (r *FuncRunner) Go(fn func(ctx context.Context) error) bool {
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done := make(chan struct{})
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go func() {
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var cancelled bool
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has := r.svc.Run(func(ctx context.Context) {
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// reset error
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r.mu.Lock()
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r.err = nil
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r.mu.Unlock()
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// Run supplied func and set errror if returned
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if err := Run(func() error { return fn(ctx) }); err != nil {
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r.mu.Lock()
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r.err = err
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r.mu.Unlock()
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}
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// signal done
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close(done)
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// Check if cancelled
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select {
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case <-ctx.Done():
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cancelled = true
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default:
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cancelled = false
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}
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})
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switch has {
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// returned after starting
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case true:
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r.mu.Lock()
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// filter out errors due FuncRunner.Stop() being called
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if cancelled && errors.Is(r.err, context.Canceled) {
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// filter out errors from FuncRunner.Stop() being called
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r.err = nil
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} else if r.err != nil && r.ErrorHandler != nil {
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// pass any non-nil error to set handler
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r.err = r.ErrorHandler(r.err)
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}
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r.mu.Unlock()
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// already running
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case false:
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close(done)
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}
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}()
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// get valid handoff to use
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handoff := r.HandOff
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if handoff < 1 {
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handoff = time.Second * 5
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}
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select {
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// handed off (long-run successful)
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case <-time.After(handoff):
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return true
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// 'fn' returned, check error
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case <-done:
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return (r.Err() == nil)
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}
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}
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// Stop will cancel the context supplied to the running function.
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func (r *FuncRunner) Stop() bool {
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return r.svc.Stop()
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}
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// Err returns the last-set error value.
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func (r *FuncRunner) Err() error {
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r.mu.Lock()
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err := r.err
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r.mu.Unlock()
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return err
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}
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// Run will execute the supplied 'fn' catching any panics. Returns either function-returned error or formatted panic.
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func Run(fn func() error) (err error) {
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defer func() {
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if r := recover(); r != nil {
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if e, ok := r.(error); ok {
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// wrap and preserve existing error
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err = fmt.Errorf("caught panic: %w", e)
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} else {
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// simply create new error fromt iface
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err = fmt.Errorf("caught panic: %v", r)
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}
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}
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}()
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// run supplied func
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err = fn()
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return
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}
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