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//===-- Communication.h -----------------------------------------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#ifndef liblldb_Communication_h_
#define liblldb_Communication_h_
#include "lldb/Host/HostThread.h"
#include "lldb/Utility/Broadcaster.h"
#include "lldb/Utility/Timeout.h"
#include "lldb/lldb-defines.h"
#include "lldb/lldb-enumerations.h"
#include "lldb/lldb-forward.h"
#include "lldb/lldb-types.h"
#include <atomic>
#include <mutex>
#include <ratio>
#include <string>
#include <stddef.h>
#include <stdint.h>
namespace lldb_private {
class Connection;
class ConstString;
class Status;
/// \class Communication Communication.h "lldb/Core/Communication.h" An
/// abstract communications class.
/// Communication is an class that handles data communication between two data
/// sources. It uses a Connection class to do the real communication. This
/// approach has a couple of advantages: it allows a single instance of this
/// class to be used even though its connection can change. Connections could
/// negotiate for different connections based on abilities like starting with
/// Bluetooth and negotiating up to WiFi if available. It also allows this
/// class to be subclassed by any interfaces that don't want to give bytes but
/// want to validate and give out packets. This can be done by overriding:
/// AppendBytesToCache (const uint8_t *src, size_t src_len, bool broadcast);
/// Communication inherits from Broadcaster which means it can be used in
/// conjunction with Listener to wait for multiple broadcaster objects and
/// multiple events from each of those objects. Communication defines a set of
/// pre-defined event bits (see enumerations definitions that start with
/// "eBroadcastBit" below).
/// There are two modes in which communications can occur:
/// \li single-threaded
/// \li multi-threaded
/// In single-threaded mode, all reads and writes happen synchronously on the
/// calling thread.
/// In multi-threaded mode, a read thread is spawned that continually reads
/// data and caches any received bytes. To start the read thread clients call:
/// bool Communication::StartReadThread (Status *);
/// If true is returned a read thread has been spawned that will continually
/// execute a call to the pure virtual DoRead function:
/// size_t Communication::ReadFromConnection (void *, size_t, uint32_t);
/// When bytes are received the data gets cached in \a m_bytes and this class
/// will broadcast a \b eBroadcastBitReadThreadGotBytes event. Clients that
/// want packet based communication should override AppendBytesToCache. The
/// subclasses can choose to call the built in AppendBytesToCache with the \a
/// broadcast parameter set to false. This will cause the \b
/// eBroadcastBitReadThreadGotBytes event not get broadcast, and then the
/// subclass can post a \b eBroadcastBitPacketAvailable event when a full
/// packet of data has been received.
/// If the connection is disconnected a \b eBroadcastBitDisconnected event
/// gets broadcast. If the read thread exits a \b
/// eBroadcastBitReadThreadDidExit event will be broadcast. Clients can also
/// post a \b eBroadcastBitReadThreadShouldExit event to this object which
/// will cause the read thread to exit.
class Communication : public Broadcaster {
eBroadcastBitDisconnected =
(1u << 0), ///< Sent when the communications connection is lost.
eBroadcastBitReadThreadGotBytes =
(1u << 1), ///< Sent by the read thread when bytes become available.
eBroadcastBitReadThreadDidExit =
<< 2), ///< Sent by the read thread when it exits to inform clients.
eBroadcastBitReadThreadShouldExit =
(1u << 3), ///< Sent by clients that need to cancel the read thread.
eBroadcastBitPacketAvailable =
(1u << 4), ///< Sent when data received makes a complete packet.
eBroadcastBitNoMorePendingInput = (1u << 5), ///< Sent by the read thread
///to indicate all pending
///input has been processed.
kLoUserBroadcastBit =
(1u << 16), ///< Subclasses can used bits 31:16 for any needed events.
kHiUserBroadcastBit = (1u << 31),
eAllEventBits = 0xffffffff};
typedef void (*ReadThreadBytesReceived)(void *baton, const void *src,
size_t src_len);
/// Construct the Communication object with the specified name for the
/// Broadcaster that this object inherits from.
/// \param[in] broadcaster_name
/// The name of the broadcaster object. This name should be as
/// complete as possible to uniquely identify this object. The
/// broadcaster name can be updated after the connect function
/// is called.
Communication(const char *broadcaster_name);
/// Destructor.
/// The destructor is virtual since this class gets subclassed.
~Communication() override;
void Clear();
/// Connect using the current connection by passing \a url to its connect
/// function. string.
/// \param[in] url
/// A string that contains all information needed by the
/// subclass to connect to another client.
/// \return
/// \b True if the connect succeeded, \b false otherwise. The
/// internal error object should be filled in with an
/// appropriate value based on the result of this function.
/// \see Status& Communication::GetError ();
/// \see bool Connection::Connect (const char *url);
lldb::ConnectionStatus Connect(const char *url, Status *error_ptr);
/// Disconnect the communications connection if one is currently connected.
/// \return
/// \b True if the disconnect succeeded, \b false otherwise. The
/// internal error object should be filled in with an
/// appropriate value based on the result of this function.
/// \see Status& Communication::GetError ();
/// \see bool Connection::Disconnect ();
lldb::ConnectionStatus Disconnect(Status *error_ptr = nullptr);
/// Check if the connection is valid.
/// \return
/// \b True if this object is currently connected, \b false
/// otherwise.
bool IsConnected() const;
bool HasConnection() const;
lldb_private::Connection *GetConnection() { return m_connection_sp.get(); }
/// Read bytes from the current connection.
/// If no read thread is running, this function call the connection's
/// Connection::Read(...) function to get any available.
/// If a read thread has been started, this function will check for any
/// cached bytes that have already been read and return any currently
/// available bytes. If no bytes are cached, it will wait for the bytes to
/// become available by listening for the \a eBroadcastBitReadThreadGotBytes
/// event. If this function consumes all of the bytes in the cache, it will
/// reset the \a eBroadcastBitReadThreadGotBytes event bit.
/// \param[in] dst
/// A destination buffer that must be at least \a dst_len bytes
/// long.
/// \param[in] dst_len
/// The number of bytes to attempt to read, and also the max
/// number of bytes that can be placed into \a dst.
/// \param[in] timeout
/// A timeout value or llvm::None for no timeout.
/// \return
/// The number of bytes actually read.
/// \see size_t Connection::Read (void *, size_t);
size_t Read(void *dst, size_t dst_len, const Timeout<std::micro> &timeout,
lldb::ConnectionStatus &status, Status *error_ptr);
/// The actual write function that attempts to write to the communications
/// protocol.
/// Subclasses must override this function.
/// \param[in] src
/// A source buffer that must be at least \a src_len bytes
/// long.
/// \param[in] src_len
/// The number of bytes to attempt to write, and also the
/// number of bytes are currently available in \a src.
/// \return
/// The number of bytes actually Written.
size_t Write(const void *src, size_t src_len, lldb::ConnectionStatus &status,
Status *error_ptr);
/// Sets the connection that it to be used by this class.
/// By making a communication class that uses different connections it
/// allows a single communication interface to negotiate and change its
/// connection without any interruption to the client. It also allows the
/// Communication class to be subclassed for packet based communication.
/// \param[in] connection
/// A connection that this class will own and destroy.
/// \see
/// class Connection
void SetConnection(Connection *connection);
/// Starts a read thread whose sole purpose it to read bytes from the
/// current connection. This function will call connection's read function:
/// size_t Connection::Read (void *, size_t);
/// When bytes are read and cached, this function will call:
/// Communication::AppendBytesToCache (const uint8_t * bytes, size_t len,
/// bool
/// broadcast);
/// Subclasses should override this function if they wish to override the
/// default action of caching the bytes and broadcasting a \b
/// eBroadcastBitReadThreadGotBytes event.
/// \return
/// \b True if the read thread was successfully started, \b
/// false otherwise.
/// \see size_t Connection::Read (void *, size_t);
/// \see void Communication::AppendBytesToCache (const uint8_t * bytes,
/// size_t len, bool broadcast);
virtual bool StartReadThread(Status *error_ptr = nullptr);
/// Stops the read thread by cancelling it.
/// \return
/// \b True if the read thread was successfully canceled, \b
/// false otherwise.
virtual bool StopReadThread(Status *error_ptr = nullptr);
virtual bool JoinReadThread(Status *error_ptr = nullptr);
/// Checks if there is a currently running read thread.
/// \return
/// \b True if the read thread is running, \b false otherwise.
bool ReadThreadIsRunning();
/// The static read thread function. This function will call the "DoRead"
/// function continuously and wait for data to become available. When data
/// is received it will append the available data to the internal cache and
/// broadcast a \b eBroadcastBitReadThreadGotBytes event.
/// \param[in] comm_ptr
/// A pointer to an instance of this class.
/// \return
/// \b NULL.
/// \see void Communication::ReadThreadGotBytes (const uint8_t *, size_t);
static lldb::thread_result_t ReadThread(lldb::thread_arg_t comm_ptr);
void SetReadThreadBytesReceivedCallback(ReadThreadBytesReceived callback,
void *callback_baton);
/// Wait for the read thread to process all outstanding data.
/// After this function returns, the read thread has processed all data that
/// has been waiting in the Connection queue.
void SynchronizeWithReadThread();
static const char *ConnectionStatusAsCString(lldb::ConnectionStatus status);
bool GetCloseOnEOF() const { return m_close_on_eof; }
void SetCloseOnEOF(bool b) { m_close_on_eof = b; }
static ConstString &GetStaticBroadcasterClass();
ConstString &GetBroadcasterClass() const override {
return GetStaticBroadcasterClass();
lldb::ConnectionSP m_connection_sp; ///< The connection that is current in use
///by this communications class.
HostThread m_read_thread; ///< The read thread handle in case we need to
///cancel the thread.
std::atomic<bool> m_read_thread_enabled;
std::atomic<bool> m_read_thread_did_exit;
m_bytes; ///< A buffer to cache bytes read in the ReadThread function.
std::recursive_mutex m_bytes_mutex; ///< A mutex to protect multi-threaded
///access to the cached bytes.
m_write_mutex; ///< Don't let multiple threads write at the same time...
std::mutex m_synchronize_mutex;
ReadThreadBytesReceived m_callback;
void *m_callback_baton;
bool m_close_on_eof;
size_t ReadFromConnection(void *dst, size_t dst_len,
const Timeout<std::micro> &timeout,
lldb::ConnectionStatus &status, Status *error_ptr);
/// Append new bytes that get read from the read thread into the internal
/// object byte cache. This will cause a \b eBroadcastBitReadThreadGotBytes
/// event to be broadcast if \a broadcast is true.
/// Subclasses can override this function in order to inspect the received
/// data and check if a packet is available.
/// Subclasses can also still call this function from the overridden method
/// to allow the caching to correctly happen and suppress the broadcasting
/// of the \a eBroadcastBitReadThreadGotBytes event by setting \a broadcast
/// to false.
/// \param[in] src
/// A source buffer that must be at least \a src_len bytes
/// long.
/// \param[in] src_len
/// The number of bytes to append to the cache.
virtual void AppendBytesToCache(const uint8_t *src, size_t src_len,
bool broadcast,
lldb::ConnectionStatus status);
/// Get any available bytes from our data cache. If this call empties the
/// data cache, the \b eBroadcastBitReadThreadGotBytes event will be reset
/// to signify no more bytes are available.
/// \param[in] dst
/// A destination buffer that must be at least \a dst_len bytes
/// long.
/// \param[in] dst_len
/// The number of bytes to attempt to read from the cache,
/// and also the max number of bytes that can be placed into
/// \a dst.
/// \return
/// The number of bytes extracted from the data cache.
size_t GetCachedBytes(void *dst, size_t dst_len);
} // namespace lldb_private
#endif // liblldb_Communication_h_