1 files changed, 224 insertions, 0 deletions
diff --git a/modules/actions/log.go b/modules/actions/log.go
new file mode 100644
index 0000000..5a1425e
--- /dev/null
+++ b/modules/actions/log.go
@@ -0,0 +1,224 @@
+// Copyright 2022 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package actions
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+	"time"
+
+	"code.gitea.io/gitea/models/dbfs"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/storage"
+	"code.gitea.io/gitea/modules/zstd"
+
+	runnerv1 "code.gitea.io/actions-proto-go/runner/v1"
+	"google.golang.org/protobuf/types/known/timestamppb"
+)
+
+const (
+	MaxLineSize = 64 * 1024
+	DBFSPrefix  = "actions_log/"
+
+	timeFormat     = "2006-01-02T15:04:05.0000000Z07:00"
+	defaultBufSize = MaxLineSize
+)
+
+// WriteLogs appends logs to DBFS file for temporary storage.
+// It doesn't respect the file format in the filename like ".zst", since it's difficult to reopen a closed compressed file and append new content.
+// Why doesn't it store logs in object storage directly? Because it's not efficient to append content to object storage.
+func WriteLogs(ctx context.Context, filename string, offset int64, rows []*runnerv1.LogRow) ([]int, error) {
+	flag := os.O_WRONLY
+	if offset == 0 {
+		// Create file only if offset is 0, or it could result in content holes if the file doesn't exist.
+		flag |= os.O_CREATE
+	}
+	name := DBFSPrefix + filename
+	f, err := dbfs.OpenFile(ctx, name, flag)
+	if err != nil {
+		return nil, fmt.Errorf("dbfs OpenFile %q: %w", name, err)
+	}
+	defer f.Close()
+
+	stat, err := f.Stat()
+	if err != nil {
+		return nil, fmt.Errorf("dbfs Stat %q: %w", name, err)
+	}
+	if stat.Size() < offset {
+		// If the size is less than offset, refuse to write, or it could result in content holes.
+		// However, if the size is greater than offset, we can still write to overwrite the content.
+		return nil, fmt.Errorf("size of %q is less than offset", name)
+	}
+
+	if _, err := f.Seek(offset, io.SeekStart); err != nil {
+		return nil, fmt.Errorf("dbfs Seek %q: %w", name, err)
+	}
+
+	writer := bufio.NewWriterSize(f, defaultBufSize)
+
+	ns := make([]int, 0, len(rows))
+	for _, row := range rows {
+		n, err := writer.WriteString(FormatLog(row.Time.AsTime(), row.Content) + "\n")
+		if err != nil {
+			return nil, err
+		}
+		ns = append(ns, n)
+	}
+
+	if err := writer.Flush(); err != nil {
+		return nil, err
+	}
+	return ns, nil
+}
+
+func ReadLogs(ctx context.Context, inStorage bool, filename string, offset, limit int64) ([]*runnerv1.LogRow, error) {
+	f, err := OpenLogs(ctx, inStorage, filename)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	if _, err := f.Seek(offset, io.SeekStart); err != nil {
+		return nil, fmt.Errorf("file seek: %w", err)
+	}
+
+	scanner := bufio.NewScanner(f)
+	maxLineSize := len(timeFormat) + MaxLineSize + 1
+	scanner.Buffer(make([]byte, maxLineSize), maxLineSize)
+
+	var rows []*runnerv1.LogRow
+	for scanner.Scan() && (int64(len(rows)) < limit || limit < 0) {
+		t, c, err := ParseLog(scanner.Text())
+		if err != nil {
+			return nil, fmt.Errorf("parse log %q: %w", scanner.Text(), err)
+		}
+		rows = append(rows, &runnerv1.LogRow{
+			Time:    timestamppb.New(t),
+			Content: c,
+		})
+	}
+
+	if err := scanner.Err(); err != nil {
+		return nil, fmt.Errorf("ReadLogs scan: %w", err)
+	}
+
+	return rows, nil
+}
+
+const (
+	// logZstdBlockSize is the block size for zstd compression.
+	// 128KB leads the compression ratio to be close to the regular zstd compression.
+	// And it means each read from the underlying object storage will be at least 128KB*(compression ratio).
+	// The compression ratio is about 30% for text files, so the actual read size is about 38KB, which should be acceptable.
+	logZstdBlockSize = 128 * 1024 // 128KB
+)
+
+// TransferLogs transfers logs from DBFS to object storage.
+// It happens when the file is complete and no more logs will be appended.
+// It respects the file format in the filename like ".zst", and compresses the content if needed.
+func TransferLogs(ctx context.Context, filename string) (func(), error) {
+	name := DBFSPrefix + filename
+	remove := func() {
+		if err := dbfs.Remove(ctx, name); err != nil {
+			log.Warn("dbfs remove %q: %v", name, err)
+		}
+	}
+	f, err := dbfs.Open(ctx, name)
+	if err != nil {
+		return nil, fmt.Errorf("dbfs open %q: %w", name, err)
+	}
+	defer f.Close()
+
+	var reader io.Reader = f
+	if strings.HasSuffix(filename, ".zst") {
+		r, w := io.Pipe()
+		reader = r
+		zstdWriter, err := zstd.NewSeekableWriter(w, logZstdBlockSize)
+		if err != nil {
+			return nil, fmt.Errorf("zstd NewSeekableWriter: %w", err)
+		}
+		go func() {
+			defer func() {
+				_ = w.CloseWithError(zstdWriter.Close())
+			}()
+			if _, err := io.Copy(zstdWriter, f); err != nil {
+				_ = w.CloseWithError(err)
+				return
+			}
+		}()
+	}
+
+	if _, err := storage.Actions.Save(filename, reader, -1); err != nil {
+		return nil, fmt.Errorf("storage save %q: %w", filename, err)
+	}
+	return remove, nil
+}
+
+func RemoveLogs(ctx context.Context, inStorage bool, filename string) error {
+	if !inStorage {
+		name := DBFSPrefix + filename
+		err := dbfs.Remove(ctx, name)
+		if err != nil {
+			return fmt.Errorf("dbfs remove %q: %w", name, err)
+		}
+		return nil
+	}
+	err := storage.Actions.Delete(filename)
+	if err != nil {
+		return fmt.Errorf("storage delete %q: %w", filename, err)
+	}
+	return nil
+}
+
+func OpenLogs(ctx context.Context, inStorage bool, filename string) (io.ReadSeekCloser, error) {
+	if !inStorage {
+		name := DBFSPrefix + filename
+		f, err := dbfs.Open(ctx, name)
+		if err != nil {
+			return nil, fmt.Errorf("dbfs open %q: %w", name, err)
+		}
+		return f, nil
+	}
+
+	f, err := storage.Actions.Open(filename)
+	if err != nil {
+		return nil, fmt.Errorf("storage open %q: %w", filename, err)
+	}
+
+	var reader io.ReadSeekCloser = f
+	if strings.HasSuffix(filename, ".zst") {
+		r, err := zstd.NewSeekableReader(f)
+		if err != nil {
+			return nil, fmt.Errorf("zstd NewSeekableReader: %w", err)
+		}
+		reader = r
+	}
+
+	return reader, nil
+}
+
+func FormatLog(timestamp time.Time, content string) string {
+	// Content shouldn't contain new line, it will break log indexes, other control chars are safe.
+	content = strings.ReplaceAll(content, "\n", `\n`)
+	if len(content) > MaxLineSize {
+		content = content[:MaxLineSize]
+	}
+	return fmt.Sprintf("%s %s", timestamp.UTC().Format(timeFormat), content)
+}
+
+func ParseLog(in string) (time.Time, string, error) {
+	index := strings.IndexRune(in, ' ')
+	if index < 0 {
+		return time.Time{}, "", fmt.Errorf("invalid log: %q", in)
+	}
+	timestamp, err := time.Parse(timeFormat, in[:index])
+	if err != nil {
+		return time.Time{}, "", err
+	}
+	return timestamp, in[index+1:], nil
+}