| 1 | package activator |
| 2 | |
| 3 | import ( |
| 4 | "io" |
| 5 | "net" |
| 6 | "os" |
| 7 | "sync" |
| 8 | "sync/atomic" |
| 9 | |
| 10 | "github.com/carlosframework/platform/internal/applog" |
| 11 | "github.com/carlosframework/platform/internal/edge" |
| 12 | ) |
| 13 | |
| 14 | // logListener is the agent's end of a unit's stdout (design §6.4): the |
| 15 | // unit's StandardOutput=file: connects to this AF_UNIX socket once, at |
| 16 | // exec, and every line is teed to the agent's own stdout (journald) and to |
| 17 | // the app log sink, exactly as teeStd does for an exec child. One |
| 18 | // connection per listener is accepted; a second is closed unread. The |
| 19 | // accepted flag never resets by design: a listener belongs to one |
| 20 | // invocation, and a re-exec of the unit gets a fresh listener from |
| 21 | // prepare. EOF ends log collection and nothing else: it is never a sign |
| 22 | // the process is gone (codex R1-4). |
| 23 | type logListener struct { |
| 24 | ln net.Listener |
| 25 | emit func(string) |
| 26 | accepted atomic.Bool |
| 27 | closed atomic.Bool |
| 28 | // conn is the one accepted connection, kept so Close can shut it and |
| 29 | // unblock the tee; wg covers the accept loop and the tee. |
| 30 | mu sync.Mutex |
| 31 | conn net.Conn |
| 32 | wg sync.WaitGroup |
| 33 | } |
| 34 | |
| 35 | func listenLogs(path string, emit func(string)) (*logListener, error) { |
| 36 | ln, err := edge.SecureUnixListen(path) |
| 37 | if err != nil { |
| 38 | return nil, err |
| 39 | } |
| 40 | l := &logListener{ln: ln, emit: emit} |
| 41 | l.wg.Add(1) |
| 42 | go l.accept() |
| 43 | return l, nil |
| 44 | } |
| 45 | |
| 46 | func (l *logListener) accept() { |
| 47 | defer l.wg.Done() |
| 48 | for { |
| 49 | c, err := l.ln.Accept() |
| 50 | if err != nil { |
| 51 | return |
| 52 | } |
| 53 | if l.accepted.Swap(true) { |
| 54 | c.Close() |
| 55 | continue |
| 56 | } |
| 57 | l.mu.Lock() |
| 58 | if l.closed.Load() { |
| 59 | // Close ran between Accept and here; nothing may outlive it. |
| 60 | l.mu.Unlock() |
| 61 | c.Close() |
| 62 | continue |
| 63 | } |
| 64 | l.conn = c |
| 65 | l.wg.Add(1) |
| 66 | l.mu.Unlock() |
| 67 | go l.tee(c) |
| 68 | } |
| 69 | } |
| 70 | |
| 71 | func (l *logListener) tee(c net.Conn) { |
| 72 | defer l.wg.Done() |
| 73 | defer c.Close() |
| 74 | var sink io.Writer = os.Stdout |
| 75 | if l.emit != nil { |
| 76 | sink = io.MultiWriter(os.Stdout, applog.NewLineWriter(execLogLineMax, l.emit)) |
| 77 | } |
| 78 | // applog.LineWriter owns line assembly and the length cap, so no |
| 79 | // buffering layer is needed between the connection and the sink. |
| 80 | _, _ = io.Copy(sink, c) |
| 81 | } |
| 82 | |
| 83 | // Exited always reports false: a log listener knows nothing about process |
| 84 | // state, and this method exists so a caller cannot mistake it for one. |
| 85 | func (l *logListener) Exited() bool { return false } |
| 86 | |
| 87 | // Close stops accepting, shuts the accepted connection so a blocked tee |
| 88 | // returns, and waits for both goroutines. Nothing spawned by the listener |
| 89 | // outlives Close: the process it belonged to is gone or being replaced, |
| 90 | // and a late line must not reach the sink under the old invocation. |
| 91 | func (l *logListener) Close() error { |
| 92 | if l.closed.Swap(true) { |
| 93 | return nil |
| 94 | } |
| 95 | err := l.ln.Close() |
| 96 | l.mu.Lock() |
| 97 | if l.conn != nil { |
| 98 | l.conn.Close() |
| 99 | } |
| 100 | l.mu.Unlock() |
| 101 | l.wg.Wait() |
| 102 | return err |
| 103 | } |
| 104 | |
amadan