github.com/unigraph-dev/dgraph@v1.1.1-0.20200923154953-8b52b426f765/testutil/exec.go

/*
 * Copyright 2019 Dgraph Labs, Inc. and Contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package testutil

import (
	"fmt"
	"io"
	"os"
	"os/exec"
	"path"

	"github.com/dgraph-io/dgraph/x"
)

// These are exported so they can also be set directly from outside this package.
var (
	ShowOutput  = os.Getenv("DEBUG_SHOW_OUTPUT") != ""
	ShowError   = os.Getenv("DEBUG_SHOW_ERROR") != ""
	ShowCommand = os.Getenv("DEBUG_SHOW_COMMAND") != ""
)

// CmdOpts sets the options to run a single command.
type CmdOpts struct {
	Dir string
}

// RepoPath converts a path relative to the root of the repo into an absolute path.
func RepoPath(p string) string {
	return path.Join(os.ExpandEnv("$GOPATH/src/github.com/dgraph-io/dgraph"), p)
}

// Exec runs a single external command.
func Exec(argv ...string) error {
	return Pipeline([][]string{argv})
}

// ExecWithOpts runs a single external command with the given options.
func ExecWithOpts(argv []string, opts CmdOpts) error {
	return pipelineInternal([][]string{argv}, []CmdOpts{opts})
}

// Pipeline runs several commands such that the output of one command becomes the input of the next.
// The first argument should be an two-dimensional array containing the commands.
// TODO: allow capturing output, sending to terminal, etc
func Pipeline(cmds [][]string) error {
	return pipelineInternal(cmds, nil)
}

// piplineInternal takes a list of commands and a list of options (one for each).
// If opts is nil, all commands should be run with the default options.
func pipelineInternal(cmds [][]string, opts []CmdOpts) error {
	x.AssertTrue(opts == nil || len(cmds) == len(opts))

	var p io.ReadCloser
	var numCmds = len(cmds)

	cmd := make([]*exec.Cmd, numCmds)

	// Run all commands in parallel, connecting stdin of each to the stdout of the previous.
	for i, c := range cmds {
		lastCmd := i == numCmds-1
		if ShowCommand {
			fmt.Fprintf(os.Stderr, "%+v", c)
		}

		cmd[i] = exec.Command(c[0], c[1:]...)
		cmd[i].Stdin = p

		if opts != nil {
			cmd[i].Dir = opts[i].Dir
		}

		if !lastCmd {
			p, _ = cmd[i].StdoutPipe()
		}

		if ShowOutput {
			cmd[i].Stderr = os.Stderr
			if lastCmd {
				cmd[i].Stdout = os.Stdout
			}
		} else if ShowError {
			cmd[i].Stderr = os.Stderr
		}

		if ShowCommand {
			if lastCmd {
				fmt.Fprintf(os.Stderr, "\n")
			} else {
				fmt.Fprintf(os.Stderr, "\n| ")
			}
		}

		err := cmd[i].Start()
		x.Check(err)
	}

	// Make sure to properly reap all spawned processes, but only save the error from the
	// earliest stage of the pipeline.
	var err error
	for i := range cmds {
		e := cmd[i].Wait()
		if e != nil && err == nil {
			err = e
		}
	}

	return err
}