f3eade2f62
Drop the AGPL license in favor of a source-available license. See the blog post [1] for details. [1] https://www.scylladb.com/2024/12/18/why-were-moving-to-a-source-available-license/
94 lines
3.6 KiB
Python
94 lines
3.6 KiB
Python
#
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# Copyright (C) 2022-present ScyllaDB
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#
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# SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
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#
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import errno
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import fcntl
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import os
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import random
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from pathlib import Path
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from test.pylib.pool import Pool
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from typing import NewType, Awaitable, Optional
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Host = NewType('Host', str)
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class HostRegistry:
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"""A Scylla servers needs a unique IP address and working directory
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which we need to manage and share across many running tests. Store
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all shared external resources within this class to make sure
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nothing is leaked by the harness. Lease addresses with lease_host(),
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release with release_host(). Each returned address is from a unique
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class-C subnet created just for this test run, so each address
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is quaranteed to have a unique 4th component. I.e. in X.Y.Z.W
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X.Y.Z is unique for each test.py invocation, and W is unique
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across all hosts in a single run.
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"""
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def __init__(self) -> None:
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# Imagine multiple instances of test.py run concurrently.
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# Each will be trying to start and stop Scylla servers.
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# If different runs share the same Scylla IP pool, Scyllas may
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# fail to bind CQL port, and tests will fail. So let's
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# give each run its own class B network in 127.*.*.* range.
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# Each scylla server will get an IP in this network.
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#
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# Why not simply give each Scylla a unique IP direved from its own
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# pid? The pid changes between restarts, and harness does start and
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# stops Scyllas.
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#
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# To create a subnet let's randomly generate a number and put
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# a file with this name into /tmp. If the file doesn't exist,
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# the subnet is free. If it already exists and is locked,
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# there is another process running with this subnet and we
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# should try again with another subnet. If the file isn't
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# locked, it remains from some previous invocation and can be
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# locked and reused.
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while True:
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# Avoid 127.0.*.* since CCM (a different test framework)
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# assumes it will be available for it to run Scylla
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# instances. 127.255.255.255 is also illegal.
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self.subnet = "127.{}.{}".format(random.randrange(1, 254),
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random.randrange(0, 255))
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self.lock_filename: Optional[Path] = Path(os.getenv('TMPDIR', '/tmp')) / ('scylla-' + self.subnet)
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self.lock_file = self.lock_filename.open('w')
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try:
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fcntl.lockf(self.lock_file, fcntl.LOCK_EX | fcntl.LOCK_NB)
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break
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except OSError as e:
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if e.errno != errno.EACCES and e.errno != errno.EAGAIN:
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raise
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self.lock_file.close()
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self.lock_filename.unlink()
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self.lock_file.close()
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self.subnet += ".{}"
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self.next_host_id = 0
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async def create_host() -> Host:
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self.next_host_id += 1
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return Host(self.subnet.format(self.next_host_id))
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async def destroy_host(h: Host) -> None:
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# Doesn't matter, we never return hosts to the pool as 'dirty'.
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pass
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self.pool = Pool[Host](254, create_host, destroy_host)
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async def cleanup() -> None:
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if self.lock_filename:
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self.lock_filename.unlink()
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self.lock_filename = None
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self.cleanup = cleanup
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async def lease_host(self) -> Host:
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return await self.pool.get()
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async def release_host(self, host: Host) -> None:
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return await self.pool.put(host, is_dirty=False)
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