Raphael Isemann
a84d94802d
[lldb] Add a packet-test-delay setting for testing slow connections Sending/receiving packets to/from a non-host devices adds latency to the gdb-remote communication that induces substantial slowdown into the debugging experience. This patch adds an artificial delay before sending a packet to simulate this latency without requiring an emulated/physical device. The test checks only checks that there is a delay when this setting is activated, but not that there is no delay when the setting is not activated. The reason for this is that this negative test would either require a large delay (which further slows down the test suite) or be prone to accidential failures on overloaded test bots. There is also the question whether we should have dynamic delays that depend on the number of transferred bytes. From talking to Felipe it seems the real bottleneck is really just the latency and not the transfer speed. From my own testing, it seems that a simple fixed array mostly simulated the remote debugging performance, and the delays I can see on my own machine seem to mostly resemble the delays we can see when debugging on a remote device. This patch also required wrapping `SendPacketAndWaitForResponse` so we can sync this setting on a per-packet basis for the GDBRemoteCommunication class. Without this, we could only set the delay before connecting and then never change afterwards which would make this feature less useful and writing a simple test impossible.
40 lines
1.3 KiB
Python
40 lines
1.3 KiB
Python
import time
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import lldb
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from lldbsuite.test.lldbtest import *
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from lldbsuite.test.decorators import *
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from lldbsuite.test.gdbclientutils import *
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from lldbsuite.test.lldbgdbclient import GDBRemoteTestBase
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class TestPacketTestDelay(GDBRemoteTestBase):
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NO_DEBUG_INFO_TESTCASE = True
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def test_packet_test_delay(self):
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"""Verify that packet-test-delay inserts a delay before each sent packet."""
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# 1000ms should be long enough that this test doesn't pass by
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# accident even on slow machines, but not too long to waste test
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# suite time.
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DELAY_MS = 1000
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class MyResponder(MockGDBServerResponder):
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def x(self, addr, length):
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return "foobar"
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self.server.responder = MyResponder()
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target = self.dbg.CreateTargetWithFileAndTargetTriple("", "x86_64-pc-linux")
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process = self.connect(target)
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error = lldb.SBError()
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start = time.time()
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self.runCmd(
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"settings set plugin.process.gdb-remote.packet-test-delay %d" % DELAY_MS
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)
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# Send a single dummy packet so we can observe the delay.
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process.ReadMemory(0x1000, 10, error)
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elapsed_ms = (time.time() - start) * 1000
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self.assertGreaterEqual(
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elapsed_ms, DELAY_MS, "Packet was sent faster than the set test delay?"
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)
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