apache-ignite

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#  Licensed to the Apache Software Foundation (ASF) under one or more
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#  contributor license agreements.  See the NOTICE file distributed with
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#  this work for additional information regarding copyright ownership.
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#  The ASF licenses this file to You under the Apache License, Version 2.0
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#  (the "License"); you may not use this file except in compliance with
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#  the License.  You may obtain a copy of the License at
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#
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#       http://www.apache.org/licenses/LICENSE-2.0
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#
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#  Unless required by applicable law or agreed to in writing, software
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#  distributed under the License is distributed on an "AS IS" BASIS,
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#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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#  See the License for the specific language governing permissions and
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#  limitations under the License.
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"""
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This module contains log utils.
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"""
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from contextlib import contextmanager
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from ducktape.cluster.remoteaccount import LogMonitor
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@contextmanager
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def monitor_log(node, log, from_the_beginning=False):
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    """
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    Context manager that returns an object that helps you wait for events to
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    occur in a log. This checks the size of the log at the beginning of the
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    block and makes a helper object available with convenience methods for
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    checking or waiting for a pattern to appear in the log. This will commonly
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    be used to start a process, then wait for a log message indicating the
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    process is in a ready state.
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    See ``LogMonitor`` for more usage information.
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    """
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    try:
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        offset = 0 if from_the_beginning else int(node.account.ssh_output("wc -c %s" % log).split()[0])
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    except Exception:
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        offset = 0
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    yield LogMonitor(node.account, log, offset)
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