Method planRun

command/sync.go:439–531

planRun prepares the commands and writes them to writer 'w'.

(
	c *cli.Context,
	onlySource, onlyDest chan *url.URL,
	common chan *ObjectPair,
	dsturl *url.URL,
	strategy SyncStrategy,
	w io.WriteCloser,
	isBatch bool,
)

// planRun prepares the commands and writes them to writer 'w'.
func (s Sync) planRun(
	c *cli.Context,
	onlySource, onlyDest chan *url.URL,
	common chan *ObjectPair,
	dsturl *url.URL,
	strategy SyncStrategy,
	w io.WriteCloser,
	isBatch bool,
) {
	defer w.Close()

	// Always use raw mode since sync command generates commands
	// from raw S3 objects. Otherwise, generated copy command will
	// try to expand given source.
	defaultFlags := map[string]interface{}{
		"raw": true,
	}

	// it should wait until both of the child goroutines for onlySource and common channels
	// are completed before closing the WriteCloser w to ensure that all URLs are processed.
	var wg sync.WaitGroup

	// only in source
	wg.Add(1)
	go func() {
		defer wg.Done()
		for srcurl := range onlySource {
			curDestURL := generateDestinationURL(srcurl, dsturl, isBatch)
			command, err := generateCommand(c, "cp", defaultFlags, srcurl, curDestURL)
			if err != nil {
				printDebug(s.op, err, srcurl, curDestURL)
				continue
			}
			fmt.Fprintln(w, command)
		}
	}()

	// both in source and destination
	wg.Add(1)
	go func() {
		defer wg.Done()
		for commonObject := range common {
			sourceObject, destObject := commonObject.src, commonObject.dst
			curSourceURL, curDestURL := sourceObject.URL, destObject.URL
			err := strategy.ShouldSync(sourceObject, destObject) // check if object should be copied.
			if err != nil {
				printDebug(s.op, err, curSourceURL, curDestURL)
				continue
			}

			command, err := generateCommand(c, "cp", defaultFlags, curSourceURL, curDestURL)
			if err != nil {
				printDebug(s.op, err, curSourceURL, curDestURL)
				continue
			}
			fmt.Fprintln(w, command)
		}
	}()