Method try_acquire

ci/util/lock_database.py:72–179

Atomic lock acquisition via BEGIN IMMEDIATE. Read lock: succeeds if no OTHER PID holds write lock. Write lock: succeeds if no OTHER PID holds any lock. Re-entrancy: same PID always succeeds (upgrade read->write if sole holder). Args: lock_name: Name iden

(
        self,
        lock_name: str,
        owner_pid: int,
        hostname: str,
        operation: str,
        mode: str = "write",
    )

            conn.close()

    def try_acquire(
        self,
        lock_name: str,
        owner_pid: int,
        hostname: str,
        operation: str,
        mode: str = "write",
    ) -> bool:
        """Atomic lock acquisition via BEGIN IMMEDIATE.

        Read lock: succeeds if no OTHER PID holds write lock.
        Write lock: succeeds if no OTHER PID holds any lock.
        Re-entrancy: same PID always succeeds (upgrade read->write if sole holder).

        Args:
            lock_name: Name identifying the lock
            owner_pid: PID of the process acquiring the lock
            hostname: Hostname of the machine
            operation: Description of the operation
            mode: Lock mode - 'read' or 'write'

        Returns:
            True if lock was acquired, False if blocked
        """
        conn = self._get_connection()
        try:
            cursor = conn.cursor()
            cursor.execute("BEGIN IMMEDIATE")

            cursor.execute(
                "SELECT owner_pid, lock_mode FROM lock_holders WHERE lock_name = ?",
                (lock_name,),
            )
            holders = cursor.fetchall()

            my_rows = [h for h in holders if h[0] == owner_pid]
            other_rows = [h for h in holders if h[0] != owner_pid]

            if mode == "read":
                # Blocked by other writer
                if any(h[1] == "write" for h in other_rows):
                    conn.rollback()
                    return False
                # Already hold read or write - re-entrant
                if my_rows:
                    conn.commit()
                    return True
                # Insert new read lock
                cursor.execute(
                    "INSERT INTO lock_holders (lock_name, owner_pid, lock_mode, operation, hostname, acquired_at) "
                    "VALUES (?, ?, 'read', ?, ?, ?)",
                    (lock_name, owner_pid, operation, hostname, time.time()),
                )
                conn.commit()
                return True

            if mode == "write":
                # Blocked by other holders