[vscode] Improve runInTerminal and support linux
Depends on D93874.
runInTerminal was using --wait-for, but it was some problems because it uses process polling looking for a single instance of the debuggee:
- it gets to know of the target late, which renders breakpoints in the main function almost impossible
- polling might fail if there are already other processes with the same name
- polling might also fail on some linux machine, as it's implemented with the ps command, and the ps command's args and output are not standard everywhere
As a better way to implement this so that it works well on Darwin and Linux, I'm using now the following process:
- lldb-vscode notices the runInTerminal, so it spawns lldb-vscode with a special flag --launch-target <target>. This flags tells lldb-vscode to wait to be attached and then it execs the target program. I'm using lldb-vscode itself to do this, because it makes finding the launcher program easier. Also no CMAKE INSTALL scripts are needed.
- Besides this, the debugger creates a temporary FIFO file where the launcher program will write its pid to. That way the debugger will be sure of which program to attach.
- Once attach happend, the debugger creates a second temporary file to notify the launcher program that it has been attached, so that it can then exec. I'm using this instead of using a signal or a similar mechanism because I don't want the launcher program to wait indefinitely to be attached in case the debugger crashed. That would pollute the process list with a lot of hanging processes. Instead, I'm setting a 20 seconds timeout (that's an overkill) and the launcher program seeks in intervals the second tepmorary file.
Some notes:
- I preferred not to use sockets because it requires a lot of code and I only need a pid. It would also require a lot of code when windows support is implemented.
- I didn't add Windows support, as I don't have a windows machine, but adding support for it should be easy, as the FIFO file can be implemented with a named pipe, which is standard on Windows and works pretty much the same way.
The existing test which didn't pass on Linux, now passes.
Differential Revision: https://reviews.llvm.org/D93951
2020-12-29 04:00:47 +08:00
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//===-- RunInTerminal.h ----------------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLDB_TOOLS_LLDB_VSCODE_RUNINTERMINAL_H
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#define LLDB_TOOLS_LLDB_VSCODE_RUNINTERMINAL_H
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#include "FifoFiles.h"
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#include <future>
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#include <thread>
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namespace lldb_vscode {
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enum RunInTerminalMessageKind {
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eRunInTerminalMessageKindPID = 0,
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eRunInTerminalMessageKindError,
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eRunInTerminalMessageKindDidAttach,
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};
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struct RunInTerminalMessage;
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struct RunInTerminalMessagePid;
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struct RunInTerminalMessageError;
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struct RunInTerminalMessageDidAttach;
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struct RunInTerminalMessage {
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RunInTerminalMessage(RunInTerminalMessageKind kind);
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virtual ~RunInTerminalMessage() = default;
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/// Serialize this object to JSON
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virtual llvm::json::Value ToJSON() const = 0;
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const RunInTerminalMessagePid *GetAsPidMessage() const;
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const RunInTerminalMessageError *GetAsErrorMessage() const;
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RunInTerminalMessageKind kind;
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};
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using RunInTerminalMessageUP = std::unique_ptr<RunInTerminalMessage>;
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struct RunInTerminalMessagePid : RunInTerminalMessage {
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RunInTerminalMessagePid(lldb::pid_t pid);
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llvm::json::Value ToJSON() const override;
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lldb::pid_t pid;
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};
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struct RunInTerminalMessageError : RunInTerminalMessage {
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RunInTerminalMessageError(llvm::StringRef error);
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llvm::json::Value ToJSON() const override;
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std::string error;
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};
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struct RunInTerminalMessageDidAttach : RunInTerminalMessage {
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RunInTerminalMessageDidAttach();
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llvm::json::Value ToJSON() const override;
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};
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class RunInTerminalLauncherCommChannel {
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public:
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RunInTerminalLauncherCommChannel(llvm::StringRef comm_file);
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/// Wait until the debug adaptor attaches.
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///
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/// \param[in] timeout
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/// How long to wait to be attached.
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//
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/// \return
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/// An \a llvm::Error object in case of errors or if this operation times
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/// out.
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llvm::Error WaitUntilDebugAdaptorAttaches(std::chrono::milliseconds timeout);
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/// Notify the debug adaptor this process' pid.
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///
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/// \return
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/// An \a llvm::Error object in case of errors or if this operation times
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/// out.
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llvm::Error NotifyPid();
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/// Notify the debug adaptor that there's been an error.
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void NotifyError(llvm::StringRef error);
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private:
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FifoFileIO m_io;
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};
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class RunInTerminalDebugAdapterCommChannel {
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public:
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RunInTerminalDebugAdapterCommChannel(llvm::StringRef comm_file);
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/// Notify the runInTerminal launcher that it was attached.
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///
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/// \return
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/// A future indicated whether the runInTerminal launcher received the
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/// message correctly or not.
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2021-01-26 06:05:04 +08:00
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std::future<lldb::SBError> NotifyDidAttach();
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[vscode] Improve runInTerminal and support linux
Depends on D93874.
runInTerminal was using --wait-for, but it was some problems because it uses process polling looking for a single instance of the debuggee:
- it gets to know of the target late, which renders breakpoints in the main function almost impossible
- polling might fail if there are already other processes with the same name
- polling might also fail on some linux machine, as it's implemented with the ps command, and the ps command's args and output are not standard everywhere
As a better way to implement this so that it works well on Darwin and Linux, I'm using now the following process:
- lldb-vscode notices the runInTerminal, so it spawns lldb-vscode with a special flag --launch-target <target>. This flags tells lldb-vscode to wait to be attached and then it execs the target program. I'm using lldb-vscode itself to do this, because it makes finding the launcher program easier. Also no CMAKE INSTALL scripts are needed.
- Besides this, the debugger creates a temporary FIFO file where the launcher program will write its pid to. That way the debugger will be sure of which program to attach.
- Once attach happend, the debugger creates a second temporary file to notify the launcher program that it has been attached, so that it can then exec. I'm using this instead of using a signal or a similar mechanism because I don't want the launcher program to wait indefinitely to be attached in case the debugger crashed. That would pollute the process list with a lot of hanging processes. Instead, I'm setting a 20 seconds timeout (that's an overkill) and the launcher program seeks in intervals the second tepmorary file.
Some notes:
- I preferred not to use sockets because it requires a lot of code and I only need a pid. It would also require a lot of code when windows support is implemented.
- I didn't add Windows support, as I don't have a windows machine, but adding support for it should be easy, as the FIFO file can be implemented with a named pipe, which is standard on Windows and works pretty much the same way.
The existing test which didn't pass on Linux, now passes.
Differential Revision: https://reviews.llvm.org/D93951
2020-12-29 04:00:47 +08:00
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/// Fetch the pid of the runInTerminal launcher.
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///
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/// \return
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/// An \a llvm::Error object in case of errors or if this operation times
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/// out.
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llvm::Expected<lldb::pid_t> GetLauncherPid();
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/// Fetch any errors emitted by the runInTerminal launcher or return a
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/// default error message if a certain timeout if reached.
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std::string GetLauncherError();
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private:
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FifoFileIO m_io;
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};
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/// Create a fifo file used to communicate the debug adaptor with
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/// the runInTerminal launcher.
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llvm::Expected<std::shared_ptr<FifoFile>> CreateRunInTerminalCommFile();
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} // namespace lldb_vscode
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#endif // LLDB_TOOLS_LLDB_VSCODE_RUNINTERMINAL_H
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