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wsrep-lib/include/wsrep/client_state.hpp
Teemu Ollakka 53638a8384 Removing assert() calls from public headers 
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/*
* Copyright (C) 2018-2019 Codership Oy <info@codership.com>
*
* This file is part of wsrep-lib.
*
* Wsrep-lib is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* Wsrep-lib is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with wsrep-lib. If not, see <https://www.gnu.org/licenses/>.
*/
/** @file client_state.hpp
*
*
* Return value conventions:
*
* The calls which may alter either client_state or associated
* transaction state will generally return zero on success and
* non-zero on failure. More detailed error information is stored
* into client state and persisted there until explicitly cleared.
*/
#ifndef WSREP_CLIENT_STATE_HPP
#define WSREP_CLIENT_STATE_HPP
#include "provider.hpp"
#include "transaction.hpp"
#include "client_id.hpp"
#include "mutex.hpp"
#include "lock.hpp"
#include "buffer.hpp"
#include "thread.hpp"
#include "xid.hpp"
#include "chrono.hpp"
namespace wsrep
{
class client_service;
class server_state;
class provider;
class condition_variable;
enum client_error
{
e_success,
e_error_during_commit,
e_deadlock_error,
e_interrupted_error,
e_size_exceeded_error,
e_append_fragment_error,
e_not_supported_error,
e_timeout_error
};
static inline const char* to_c_string(enum client_error error)
{
switch (error)
{
case e_success: return "success";
case e_error_during_commit: return "commit_error";
case e_deadlock_error: return "deadlock_error";
case e_interrupted_error: return "interrupted_error";
case e_size_exceeded_error: return "size_exceeded_error";
case e_append_fragment_error: return "append_fragment_error";
case e_not_supported_error: return "not_supported_error";
case e_timeout_error: return "timeout_error";
}
return "unknown";
}
static inline std::string to_string(enum client_error error)
{
return to_c_string(error);
}
/**
* Client State
*/
class client_state
{
public:
/**
* Client mode enumeration.
*/
enum mode
{
/** undefined mode */
m_undefined,
/** Locally operating client session. */
m_local,
/** High priority mode */
m_high_priority,
/** Client is in total order isolation mode */
m_toi,
/** Client is executing rolling schema upgrade */
m_rsu,
/** Client is executing NBO */
m_nbo
};
static const int n_modes_ = m_nbo + 1;
/**
* Client state enumeration.
*
*/
enum state
{
/**
* Client session has not been initialized yet.
*/
s_none,
/**
* Client is idle, the control is in the application which
* uses the DBMS system.
*/
s_idle,
/**
* The control of the client processing is inside the DBMS
* system.
*/
s_exec,
/**
* Client handler is sending result to client.
*/
s_result,
/**
* The client session is terminating.
*/
s_quitting
};
static const int state_max_ = s_quitting + 1;
/**
* Aqcuire ownership on the thread.
*
* This method should be called every time the thread
* operating the client state changes. This method is called
* implicitly from before_command() and
* wait_rollback_complete_and_acquire_ownership().
*/
void acquire_ownership()
{
wsrep::unique_lock<wsrep::mutex> lock(mutex_);
do_acquire_ownership(lock);
}
/**
* @deprecated Use acquire_ownership() instead.
*/
void store_globals()
{
acquire_ownership();
}
/**
* Destructor.
*/
virtual ~client_state();
/** @name Client session handling */
/** @{ */
/**
* This method should be called when opening the client session.
*
* Initializes client id and changes the state to s_idle.
*/
void open(wsrep::client_id);
/**
* This method should be called before closing the client session.
*
* The state is changed to s_quitting and any open transactions
* are rolled back.
*/
void close();
/**
* This method should be called after closing the client session
* to clean up.
*
* The state is changed to s_none.
*/
void cleanup();
/**
* Overload of cleanup() method which takes lock as argument.
* This method does not release the lock during execution, but
* the lock is needed for debug build sanity checks.
*/
void cleanup(wsrep::unique_lock<wsrep::mutex>& lock);
/** @} */
/** @name Client command handling */
/** @{ */
/**
* This mehod should be called before the processing of command
* received from DBMS client starts.
*
* This method will wait until the possible synchronous
* rollback for associated transaction has finished unless
* wait_rollback_complete_and_acquire_ownership() has been
* called before.
*
* The method has a side effect of changing the client
* context state to executing.
*
* The value set by keep_command_error has an effect on
* how before_command() behaves when it is entered after
* background rollback has been processed:
*
* - If keep_command_error is set true, the current error
* is set and success will be returned.
* - If keep_command_error is set false, the transaction is
* cleaned up and the return value will be non-zero to
* indicate error.
*
* @param keep_command_error Make client state to preserve error
* state in command hooks.
* This is needed if a current command is not supposed to
* return an error status to the client and the protocol must
* advance until the next client command to return error status.
*
* @return Zero in case of success, non-zero in case of the
* associated transaction was BF aborted.
*/
int before_command(bool keep_command_error);
int before_command()
{
return before_command(false);
}
/**
* This method should be called before returning
* a result to DBMS client.
*
* The method will check if the transaction associated to
* the connection has been aborted. Rollback is performed
* if needed. After the call, current_error() will return an error
* code associated to the client state. If the error code is
* not success, the transaction associated to the client state
* has been aborted and rolled back.
*/
void after_command_before_result();
/**
* Method which should be called after returning the
* control back to DBMS client..
*
* The method will do the check if the transaction associated
* to the connection has been aborted. If so, rollback is
* performed and the transaction is left to aborted state.
* The next call to before_command() will return an error and
* the error state can be examined after after_command_before_resul()
* is called.
*
* This method has a side effect of changing state to
* idle.
*/
void after_command_after_result();
/** @} */
/** @name Statement level operations */
/** @{ */
/**
* Before statement execution operations.
*
* Check if server is synced and if dirty reads are allowed.
*
* @return Zero in case of success, non-zero if the statement
* is not allowed to be executed due to read or write
* isolation requirements.
*/
int before_statement();
/**
* After statement execution operations.
*
* * Check for must_replay state
* * Do rollback if requested
*/
int after_statement();
/** @} */
/**
* Perform cleanup after applying a transaction.
*
* @param err Applying error (empty for no error)
*/
void after_applying();
/** @name Replication interface */
/** @{ */
/**
* Start a new transaction with a transaction id.
*
* @todo This method should
* - Register the transaction on server level for bookkeeping
* - Isolation levels? Or part of the transaction?
*/
int start_transaction(const wsrep::transaction_id& id);
/**
* Establish read view ID of the transaction.
*
* This method should be preferably called immediately before any
* first read or write operation in the transaction is performed,
* Then it can be called with default NULL parameter and will use
* the current last committed GTID.
* Alternatively it can be called at any time before commit with an
* explicit GTID that corresponds to transaction read view.
*
* @param gtid optional explicit GTID of the transaction read view.
*/
int assign_read_view(const wsrep::gtid* const gtid = NULL);
/**
* Append a key into transaction write set.
*
* @param key Key to be appended
*
* @return Zero on success, non-zero on failure.
*/
int append_key(const wsrep::key& key);
/**
* Append keys in key_array into transaction write set.
*
* @param keys Array of keys to be appended
*
* @return Zero in case of success, non-zero on failure.
*/
int append_keys(const wsrep::key_array& keys);
/**
* Append data into transaction write set.
*/
int append_data(const wsrep::const_buffer& data);
/** @} */
/** @name Streaming replication interface */
/** @{ */
/**
* This method should be called after every row operation.
*/
int after_row();
/**
* Set streaming parameters.
*
* @param fragment_unit Desired fragment unit
* @param fragment_size Desired fragment size
*/
void streaming_params(enum wsrep::streaming_context::fragment_unit
fragment_unit,
size_t fragment_size);
/**
* Enable streaming replication.
*
* Currently it is not possible to change the fragment unit
* for active streaming transaction.
*
* @param fragment_unit Desired fragment unit
* @param fragment_size Desired fragment size
*
* @return Zero on success, non-zero if the streaming cannot be
* enabled.
*/
int enable_streaming(
enum wsrep::streaming_context::fragment_unit
fragment_unit,
size_t fragment_size);
/**
* Disable streaming for context.
*/
void disable_streaming();
void fragment_applied(wsrep::seqno seqno);
/**
* Prepare write set meta data for ordering.
* This method should be called before ordered commit or
* rollback if the commit time meta data was not known
* at the time of the start of the transaction.
* This mostly applies to streaming replication.
*
* @param ws_handle Write set handle
* @param ws_meta Write set meta data
* @param is_commit Boolean to denote whether the operation
* is commit or rollback.
*/
int prepare_for_ordering(const wsrep::ws_handle& ws_handle,
const wsrep::ws_meta& ws_meta,
bool is_commit);
/** @} */
/** @name Applying interface */
/** @{ */
int start_transaction(const wsrep::ws_handle& wsh,
const wsrep::ws_meta& meta);
int next_fragment(const wsrep::ws_meta& meta);
/** @name Commit ordering interface */
/** @{ */
int before_prepare();
int after_prepare();
int before_commit();
int ordered_commit();
int after_commit();
/** @} */
int before_rollback();
int after_rollback();
/**
* This method should be called by the background rollbacker
* thread after the rollback is complete. This will allow
* the client to proceed through before_command() and
* wait_rollback_complete_and_acquire_ownership().
*/
void sync_rollback_complete();
/**
* Wait for background rollback to complete. This method can
* be called before before_command() to verify that the
* background rollback has been finished. After the call returns,
* it is guaranteed that BF abort does not launch background
* rollback process before after_command_after_result() is called.
* This method is idempotent, it can be called many times
* by the same thread before before_command() is called.
*/
void wait_rollback_complete_and_acquire_ownership();
/** @} */
//
// XA
//
/**
* Assign transaction external id.
*
* Other than storing the xid, the transaction is marked as XA.
* This should be called when XA transaction is started.
*
* @param xid transaction id
*/
void assign_xid(const wsrep::xid& xid)
{
transaction_.assign_xid(xid);
}
/**
* Restores the client's transaction to prepared state
*
* The purpose of this method is to restore transaction state
* during recovery of a prepared XA transaction.
*/
int restore_xid(const wsrep::xid& xid)
{
return transaction_.restore_to_prepared_state(xid);
}
/**
* Commit transaction with the given xid
*
* Sends a commit fragment to terminate the transaction with
* the given xid. For the fragment to be sent, a streaming
* applier for the transaction must exist, and the transaction
* must be in prepared state.
*
* @param xid the xid of the the transaction to commit
*
* @return Zero on success, non-zero on error. In case of error
* the client_state's current_error is set
*/
int commit_by_xid(const wsrep::xid& xid)
{
return transaction_.commit_or_rollback_by_xid(xid, true);
}
/**
* Rollback transaction with the given xid
*
* Sends a rollback fragment to terminate the transaction with
* the given xid. For the fragment to be sent, a streaming
* applier for the transaction must exist, and the transaction
* must be in prepared state.
*
* @param xid the xid of the the transaction to commit
*
* @return Zero on success, non-zero on error. In case of error
* the client_state's current_error is set
*/
int rollback_by_xid(const wsrep::xid& xid)
{
return transaction_.commit_or_rollback_by_xid(xid, false);
}
/**
* Detach a prepared XA transaction
*
* This method cleans up a local XA transaction in prepared state
* and converts it to high priority mode.
* This can be used to handle the case where the client of a XA
* transaction disconnects, and the transaction must not rollback.
* After this call, a different client may later attempt to terminate
* the transaction by calling method commit_by_xid() or rollback_by_xid().
*/
void xa_detach();
/**
* Replay a XA transaction
*
* Replay a XA transaction that is in s_idle state.
* This may happen if the transaction is BF aborted
* between prepare and commit.
* Since the victim is idle, this method can be called
* by the BF aborter or the backround rollbacker.
*/
void xa_replay();
//
// BF aborting
//
/**
* Brute force abort a transaction. This method should be
* called by a transaction which needs to BF abort a conflicting
* locally processing transaction.
*/
int bf_abort(wsrep::seqno bf_seqno);
/**
* Brute force abort a transaction in total order. This method
* should be called by the TOI operation which needs to
* BF abort a transaction.
*/
int total_order_bf_abort(wsrep::seqno bf_seqno);
/**
* Adopt a streaming transaction state. This is must be
* called from high_priority_service::adopt_transaction()
* during streaming transaction rollback. The call will
* set up enough context for handling the rollback
* fragment.
*/
void adopt_transaction(const wsrep::transaction& transaction);
/**
* Adopt (store) transaction applying error for further processing.
*/
void adopt_apply_error(wsrep::mutable_buffer& err);
/**
* Clone enough state from another transaction so that replaing will
* be possible with a transaction contained in this client state.
*
* @param transaction Transaction which is to be replied in this
* client state
*/
void clone_transaction_for_replay(const wsrep::transaction& transaction)
{
transaction_.clone_for_replay(transaction);
}
/** @name Non-transactional operations */
/** @{*/
/**
* Enter total order isolation critical section. If the wait_until
* is given non-default value, the operation is retried until
* successful, the given time point is reached or the client is
* interrupted.
*
* @param key_array Array of keys
* @param buffer Buffer containing the action to execute inside
* total order isolation section
* @param flags Provider flags for TOI operation
* @param wait_until Time point to wait until for successful
* certification.
*
* @return Zero on success, non-zero otherwise.
*/
int enter_toi_local(
const wsrep::key_array& key_array,
const wsrep::const_buffer& buffer,
std::chrono::time_point<wsrep::clock>
wait_until =
std::chrono::time_point<wsrep::clock>());
/**
* Enter applier TOI mode
*
* @param ws_meta Write set meta data
*/
void enter_toi_mode(const wsrep::ws_meta& ws_meta);
/**
* Return true if the client_state is under TOI operation.
*/
bool in_toi() const
{
return (toi_meta_.seqno().is_undefined() == false);
}
/**
* Return the mode where client entered into TOI mode.
* The return value can be either m_local or
* m_high_priority.
*/
enum mode toi_mode() const
{
return toi_mode_;
}
/**
* Leave total order isolation critical section.
* (for local mode clients)
*
* @param err definition of the error that happened during the
* execution of TOI operation (empty for no error)
*/
int leave_toi_local(const wsrep::mutable_buffer& err);
/**
* Leave applier TOI mode.
*/
void leave_toi_mode();
/**
* Begin rolling schema upgrade operation.
*
* @param timeout Timeout in seconds to wait for committing
* connections to finish.
*/
int begin_rsu(int timeout);
/**
* End rolling schema upgrade operation.
*/
int end_rsu();
/**
* Begin non-blocking operation.
*
* The NBO operation is started by grabbing TOI critical
* section. The keys and buffer are certifed as in TOI
* operation. If the call fails due to error returned by
* the provider, the provider error code can be retrieved
* by current_error_status() call.
*
* If the wait_until is given non-default value, the operation is
* retried until successful, the given time point is reached or the
* client is interrupted.
*
* @param keys Array of keys for NBO operation.
* @param buffer NBO write set
* @param wait_until Time point to wait until for successful certification.
* @return Zero in case of success, non-zero in case of failure.
*/
int begin_nbo_phase_one(
const wsrep::key_array& keys,
const wsrep::const_buffer& buffer,
std::chrono::time_point<wsrep::clock>
wait_until =
std::chrono::time_point<wsrep::clock>());
/**
* End non-blocking operation phase after aquiring required
* resources for operation.
*
* @param err definition of the error that happened during the
* execution of phase one (empty for no error)
*/
int end_nbo_phase_one(const wsrep::mutable_buffer& err);
/**
* Enter in NBO mode. This method should be called when the
* applier launches the asynchronous process to perform the
* operation. The purpose of the call is to adjust
* the state and set write set meta data.
*
* @param ws_meta Write set meta data.
*
* @return Zero in case of success, non-zero on failure.
*/
int enter_nbo_mode(const wsrep::ws_meta& ws_meta);
/**
* Begin non-blocking operation phase two. The keys argument
* passed to this call must contain the same keys which were
* passed to begin_nbo_phase_one().
*
* If the wait_until is given non-default value, the operation is
* retried until successful, the given time point is reached or the
* client is interrupted.
*
* @param keys Key array.
* @param wait_until Time point to wait until for entering TOI for
* phase two.
*/
int begin_nbo_phase_two(const wsrep::key_array& keys,
std::chrono::time_point<wsrep::clock>
wait_until =
std::chrono::time_point<wsrep::clock>());
/**
* End non-blocking operation phase two. This call will
* release TOI critical section and set the mode to m_local.
*
* @param err definition of the error that happened during the
* execution of phase two (empty for no error)
*/
int end_nbo_phase_two(const wsrep::mutable_buffer& err);
/**
* Get reference to the client mutex.
*
* @return Reference to the client mutex.
*/
wsrep::mutex& mutex() { return mutex_; }
/**
* Get server context associated the the client session.
*
* @return Reference to server context.
*/
wsrep::server_state& server_state() const
{ return server_state_; }
wsrep::client_service& client_service() const
{ return client_service_; }
/**
* Get reference to the Provider which is associated
* with the client context.
*
* @return Reference to the provider.
* @throw wsrep::runtime_error if no providers are associated
* with the client context.
*
* @todo Should be removed.
*/
wsrep::provider& provider() const;
/**
* Get Client identifier.
*
* @return Client Identifier
*/
client_id id() const { return id_; }
/**
* Get Client mode.
*
* @todo Enforce mutex protection if called from other threads.
*
* @return Client mode.
*/
enum mode mode() const { return mode_; }
/**
* Get Client state.
*
* @todo Enforce mutex protection if called from other threads.
*
* @return Client state
*/
enum state state() const { return state_; }
/**
* Return a const reference to the transaction associated
* with the client state.
*/
const wsrep::transaction& transaction() const
{
return transaction_;
}
/**
* Mark the transaction associated with the client state
* (if any), as unsafe for parallel applying
*
* @return Zero on success, non-zero on error.
*/
int mark_transaction_pa_unsafe()
{
if (transaction_.active())
{
transaction_.pa_unsafe(true);
return 0;
}
return 1;
}
const wsrep::ws_meta& toi_meta() const
{
return toi_meta_;
}
/**
* Do sync wait operation. If the method fails, current_error()
* can be inspected about the reason of error.
*
* @param Sync wait timeout in seconds.
*
* @return Zero on success, non-zero on error.
*/
int sync_wait(int timeout);
/**
* Return the current sync wait GTID.
*
* Sync wait GTID is updated on each sync_wait() call and
* reset to wsrep::gtid::undefined() in after_command_after_result()
* method. The variable can thus be used to check if a sync wait
* has been performend for the current client command.
*/
const wsrep::gtid& sync_wait_gtid() const
{
return sync_wait_gtid_;
}
/**
* Return the last written GTID.
*/
const wsrep::gtid& last_written_gtid() const
{
return last_written_gtid_;
}
/**
* Set debug logging level.
*
* Levels:
* 0 - Debug logging is disabled
* 1..n - Debug logging with increasing verbosity.
*/
void debug_log_level(int level) { debug_log_level_ = level; }
/**
* Return current debug logging level. The return value
* is a maximum of client state and server state debug log
* levels.
*
* @return Current debug log level.
*/
int debug_log_level() const
{
return std::max(debug_log_level_,
wsrep::log::debug_log_level());
}
//
// Error handling
//
/**
* Reset the current error state.
*
* @todo There should be some protection about when this can
* be done.
*/
void reset_error()
{
current_error_ = wsrep::e_success;
}
/**
* Return current error code.
*
* @return Current error code.
*/
enum wsrep::client_error current_error() const
{
return current_error_;
}
enum wsrep::provider::status current_error_status() const
{
return current_error_status_;
}
protected:
/**
* Client context constuctor. This is protected so that it
* can be called from derived class constructors only.
*/
client_state(wsrep::mutex& mutex,
wsrep::condition_variable& cond,
wsrep::server_state& server_state,
wsrep::client_service& client_service,
const client_id& id,
enum mode mode)
: owning_thread_id_(wsrep::this_thread::get_id())
, rollbacker_active_(false)
, mutex_(mutex)
, cond_(cond)
, server_state_(server_state)
, client_service_(client_service)
, id_(id)
, mode_(mode)
, toi_mode_(m_undefined)
, state_(s_none)
, state_hist_()
, transaction_(*this)
, toi_meta_()
, nbo_meta_()
, allow_dirty_reads_()
, sync_wait_gtid_()
, last_written_gtid_()
, debug_log_level_(0)
, current_error_(wsrep::e_success)
, current_error_status_(wsrep::provider::success)
, keep_command_error_()
{ }
private:
client_state(const client_state&);
client_state& operator=(client_state&);
friend class client_state_switch;
friend class high_priority_context;
friend class transaction;
void do_acquire_ownership(wsrep::unique_lock<wsrep::mutex>& lock);
// Wait for sync rollbacker to finish, with lock. Changes state
// to exec.
void do_wait_rollback_complete_and_acquire_ownership(
wsrep::unique_lock<wsrep::mutex>& lock);
void update_last_written_gtid(const wsrep::gtid&);
void debug_log_state(const char*) const;
void debug_log_keys(const wsrep::key_array& keys) const;
void state(wsrep::unique_lock<wsrep::mutex>& lock, enum state state);
void mode(wsrep::unique_lock<wsrep::mutex>& lock, enum mode mode);
// Override current client error status. Optionally provide
// an error status from the provider if the error was caused
// by the provider call.
void override_error(enum wsrep::client_error error,
enum wsrep::provider::status status =
wsrep::provider::success);
// Poll provider::enter_toi() until return status from provider
// does not indicate certification failure, timeout expires
// or client is interrupted.
enum wsrep::provider::status
poll_enter_toi(wsrep::unique_lock<wsrep::mutex>& lock,
const wsrep::key_array& keys,
const wsrep::const_buffer& buffer,
wsrep::ws_meta& meta,
int flags,
std::chrono::time_point<wsrep::clock> wait_until,
bool& timed_out);
void enter_toi_common(wsrep::unique_lock<wsrep::mutex>&);
void leave_toi_common();
wsrep::thread::id owning_thread_id_;
bool rollbacker_active_;
wsrep::mutex& mutex_;
wsrep::condition_variable& cond_;
wsrep::server_state& server_state_;
wsrep::client_service& client_service_;
wsrep::client_id id_;
enum mode mode_;
enum mode toi_mode_;
enum state state_;
std::vector<enum state> state_hist_;
wsrep::transaction transaction_;
wsrep::ws_meta toi_meta_;
wsrep::ws_meta nbo_meta_;
bool allow_dirty_reads_;
wsrep::gtid sync_wait_gtid_;
wsrep::gtid last_written_gtid_;
int debug_log_level_;
enum wsrep::client_error current_error_;
enum wsrep::provider::status current_error_status_;
bool keep_command_error_;
/**
* Marks external rollbacker thread for the client
* as active. This will block client in before_command(), until
* rolbacker has released the client.
*/
void set_rollbacker_active(bool value)
{
rollbacker_active_ = value;
}
bool is_rollbacker_active()
{
return rollbacker_active_;
}
};
static inline const char* to_c_string(
enum wsrep::client_state::state state)
{
switch (state)
{
case wsrep::client_state::s_none: return "none";
case wsrep::client_state::s_idle: return "idle";
case wsrep::client_state::s_exec: return "exec";
case wsrep::client_state::s_result: return "result";
case wsrep::client_state::s_quitting: return "quit";
}
return "unknown";
}
static inline std::string to_string(enum wsrep::client_state::state state)
{
return to_c_string(state);
}
static inline const char* to_c_string(enum wsrep::client_state::mode mode)
{
switch (mode)
{
case wsrep::client_state::m_undefined: return "undefined";
case wsrep::client_state::m_local: return "local";
case wsrep::client_state::m_high_priority: return "high priority";
case wsrep::client_state::m_toi: return "toi";
case wsrep::client_state::m_rsu: return "rsu";
case wsrep::client_state::m_nbo: return "nbo";
}
return "unknown";
}
static inline std::string to_string(enum wsrep::client_state::mode mode)
{
return to_c_string(mode);
}
/**
* Utility class to switch the client state to high priority
* mode. The client is switched back to the original mode
* when the high priority context goes out of scope.
*/
class high_priority_context
{
public:
high_priority_context(wsrep::client_state& client);
virtual ~high_priority_context();
private:
wsrep::client_state& client_;
enum wsrep::client_state::mode orig_mode_;
};
}
#endif // WSREP_CLIENT_STATE_HPP
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