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servermanager.go
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servermanager.go
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package servermanager
import (
"context"
"errors"
"fmt"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
"strconv"
"sync"
"time"
"github.com/bazel-contrib/rules_jvm/java/gazelle/private/bazel"
pb "github.com/bazel-contrib/rules_jvm/java/gazelle/private/javaparser/proto/gazelle/java/javaparser/v0"
"google.golang.org/grpc"
)
type ServerManager struct {
workspace string
javaLogLevel string
mu sync.Mutex
conn *grpc.ClientConn
}
func New(workspace, javaLogLevel string) *ServerManager {
return &ServerManager{
workspace: workspace,
javaLogLevel: javaLogLevel,
}
}
func (m *ServerManager) Connect() (*grpc.ClientConn, error) {
m.mu.Lock()
defer m.mu.Unlock()
if m.conn != nil {
return m.conn, nil
}
logLevelFlag := fmt.Sprintf("-Dorg.slf4j.simpleLogger.defaultLogLevel=%s", m.javaLogLevel)
javaParserPath, found := bazel.FindBinary("java/src/com/github/bazel_contrib/contrib_rules_jvm/javaparser/generators", "Main")
if !found {
return nil, fmt.Errorf("failed to find javaparser in runfiles")
}
dir, err := ioutil.TempDir(os.Getenv("TMPDIR"), "gazelle-javaparser")
if err != nil {
return nil, fmt.Errorf("failed to create tmpdir to start javaparser server: %w", err)
}
portFilePath := filepath.Join(dir, "port")
cmd := exec.Command(
javaParserPath,
"--jvm_flag="+logLevelFlag,
"--server-port-file-path", portFilePath,
"--workspace", m.workspace,
"--idle-timeout", "30")
// Send JavaParser stdout to stderr for two reasons:
// 1. We don't want to pollute our own stdout
// 2. Java does some output buffer sniffing where it will block its own progress until the
// stdout buffer is read from, whereas stderr is unbuffered so doesn't hit this issue.
cmd.Stdout = os.Stderr
cmd.Stderr = os.Stderr
if err := cmd.Start(); err != nil {
return nil, fmt.Errorf("failed to start javaparser sever: %w", err)
}
port, err := readPort(portFilePath)
if err != nil {
return nil, fmt.Errorf("failed to read port from javaparser server - maybe it crashed: %w", err)
}
addr := fmt.Sprintf("localhost:%d", port)
conn, err := grpc.DialContext(context.Background(), addr, grpc.WithInsecure(), grpc.WithBlock())
if err != nil {
return nil, fmt.Errorf("failed to connect to javaparser server: %w", err)
}
m.conn = conn
return conn, nil
}
func readPort(path string) (int32, error) {
startTime := time.Now()
for {
if time.Now().Sub(startTime) > 10*time.Second {
return 0, fmt.Errorf("timed out waiting for port file to be written by javaparser server")
}
bs, err := ioutil.ReadFile(path)
if err != nil {
if errors.Is(err, os.ErrNotExist) {
time.Sleep(10 * time.Millisecond)
continue
}
return 0, err
} else {
portStr := string(bs)
port, err := strconv.ParseInt(portStr, 10, 32)
if err != nil {
return 0, fmt.Errorf("error parsing port (%q) written by javaparser server: %w", portStr, err)
}
return int32(port), nil
}
}
}
func (m *ServerManager) Shutdown() {
m.mu.Lock()
defer m.mu.Unlock()
if m.conn == nil {
return
}
cc := pb.NewLifecycleClient(m.conn)
// If shutdown returns an error, there's really nothing for us to do.
cc.Shutdown(context.Background(), &pb.ShutdownRequest{})
m.conn.Close()
m.conn = nil
}