Source code of the server side

gistfile1.go

	// Search the record in the database by the file name
	recordInDB, found := search(local.FilePath)

	var compareRs int // The resule, which one to use, client side version or server side version
	var execRs bool // If the operation is failed due to concurrency, so the client side can re do the request again
	var newVersion int64 // Tell the client side the result of new version

	// If the file previously exists
	if found {
		// The compare logic to find out who wins (client or server)
		compareRs = (&recordInDB).CompareToLocal(&local)

		// If the local version win, update the database, and return a new version.
		if compareRs == common.COMPARE_LOCAL_WIN {
			execRs, newVersion = update(&local, recordInDB.Version)
		} else {
			// If the server side win, return the server side version
			execRs, newVersion = true, recordInDB.Version
		}
	} else {
		// If the file not exists in the database, the local always wins, and the init version is default to zero
		compareRs = common.COMPARE_LOCAL_WIN
		execRs, newVersion = insert(&local), 0
	}

	// return three variables to the client side, so the client side program can decide what to do accordingly
	return c.RenderJson(common.FileUpdateReturn {
		CompareRs: compareRs,
		ExecRs: execRs,
		NewVersion: newVersion,
	})