feat: implement worker

1 files changed, 186 insertions, 0 deletions

diff --git a/worker/exec.go b/worker/exec.go
new file mode 100644
index 0000000..2ef16fa
--- /dev/null
+++ b/worker/exec.go
@@ -0,0 +1,186 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"crypto/md5"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"time"
+)
+
+const (
+	dataRootDir = "/app/data"
+	// Stores *.swift files.
+	dataSwiftRootDir = dataRootDir + "/swift"
+	// Stores *.wasm files.
+	dataWasmRootDir = dataRootDir + "/wasm"
+	// Stores *.cwasm files (compiled wasm generated by "wasmtime compile").
+	dataCwasmRootDir = dataRootDir + "/cwasm"
+
+	wasmMaxMemorySize = 10 * 1024 * 1024 // 10 MiB
+)
+
+func prepareDirectories() error {
+	if err := os.MkdirAll(dataSwiftRootDir, 0755); err != nil {
+		return err
+	}
+	if err := os.MkdirAll(dataWasmRootDir, 0755); err != nil {
+		return err
+	}
+	if err := os.MkdirAll(dataCwasmRootDir, 0755); err != nil {
+		return err
+	}
+	return nil
+}
+
+func calcHash(code string) string {
+	return fmt.Sprintf("%x", md5.Sum([]byte(code)))
+}
+
+func calcFilePath(hash, ext string) string {
+	return fmt.Sprintf("%s/%s/%s.%s", dataRootDir, ext, hash, ext)
+}
+
+func execCommandWithTimeout(
+	ctx context.Context,
+	maxDuration time.Duration,
+	makeCmd func(context.Context) *exec.Cmd,
+) (string, string, error) {
+	ctx, cancel := context.WithTimeout(ctx, maxDuration)
+	defer cancel()
+
+	cmd := makeCmd(ctx)
+
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+
+	exitCh := make(chan error)
+	go func() {
+		exitCh <- cmd.Run()
+	}()
+
+	select {
+	case <-ctx.Done():
+		return stdout.String(), stderr.String(), ctx.Err()
+	case err := <-exitCh:
+		return stdout.String(), stderr.String(), err
+	}
+}
+
+func convertCommandErrorToResultType(err error) string {
+	if err != nil {
+		if err == context.DeadlineExceeded {
+			return resultTimeout
+		} else {
+			return resultFailure
+		}
+	} else {
+		return resultSuccess
+	}
+}
+
+func execSwiftCompile(
+	ctx context.Context,
+	code string,
+	maxDuration time.Duration,
+) swiftCompileResponseData {
+	hash := calcHash(code)
+	inPath := calcFilePath(hash, "swift")
+	outPath := calcFilePath(hash, "wasm")
+
+	if err := os.WriteFile(inPath, []byte(code), 0644); err != nil {
+		return swiftCompileResponseData{
+			Result: resultInternalError,
+			Stdout: "",
+			Stderr: err.Error(),
+		}
+	}
+
+	stdout, stderr, err := execCommandWithTimeout(
+		ctx,
+		maxDuration,
+		func(ctx context.Context) *exec.Cmd {
+			return exec.CommandContext(
+				ctx,
+				"swiftc",
+				"-target", "wasm32-unknown-wasi",
+				"-o", outPath,
+				inPath,
+			)
+		},
+	)
+
+	return swiftCompileResponseData{
+		Result: convertCommandErrorToResultType(err),
+		Stdout: stdout,
+		Stderr: stderr,
+	}
+}
+
+func execWasmCompile(
+	ctx context.Context,
+	code string,
+	maxDuration time.Duration,
+) wasmCompileResponseData {
+	hash := calcHash(code)
+	inPath := calcFilePath(hash, "wasm")
+	outPath := calcFilePath(hash, "cwasm")
+
+	stdout, stderr, err := execCommandWithTimeout(
+		ctx,
+		maxDuration,
+		func(ctx context.Context) *exec.Cmd {
+			return exec.CommandContext(
+				ctx,
+				"wasmtime", "compile",
+				"-O", "opt-level=0",
+				"-C", "cache=n",
+				"-W", fmt.Sprintf("max-memory-size=%d", wasmMaxMemorySize),
+				"-o", outPath,
+				inPath,
+			)
+		},
+	)
+
+	return wasmCompileResponseData{
+		Result: convertCommandErrorToResultType(err),
+		Stdout: stdout,
+		Stderr: stderr,
+	}
+}
+
+func execTestRun(
+	ctx context.Context,
+	code string,
+	stdin string,
+	maxDuration time.Duration,
+) testRunResponseData {
+	hash := calcHash(code)
+	inPath := calcFilePath(hash, "cwasm")
+
+	stdout, stderr, err := execCommandWithTimeout(
+		ctx,
+		maxDuration,
+		func(ctx context.Context) *exec.Cmd {
+			cmd := exec.CommandContext(
+				ctx,
+				"wasmtime", "run",
+				"--allow-precompiled",
+				inPath,
+			)
+			cmd.Stdin = strings.NewReader(stdin)
+			return cmd
+		},
+	)
+
+	return testRunResponseData{
+		Result: convertCommandErrorToResultType(err),
+		Stdout: stdout,
+		Stderr: stderr,
+	}
+}