f166b50b37
The fact that a client dcb was immediately added to the epoll- instance of the relevant worker (possible, since that is thread- safe), but was added to the book-keeping via the message mechanism (necessary, since that is not thread-safe), meant that if the connection was closed before the message was delivered, the handling of the message then caused an access error. Now the fd is also added to the epoll-instance via the messaging mechanism, so the problem can no longer occur. The only fds this affects are connections made to maxadmin or maxinfo as they are always handled by the main thread due to deadlock issues.
409 lines
16 KiB
C
409 lines
16 KiB
C
#pragma once
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/*
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* Copyright (c) 2016 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
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*
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* Change Date: 2020-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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/**
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* @file dcb.h The Descriptor Control Block
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*/
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#include <maxscale/cdefs.h>
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#include <maxscale/spinlock.h>
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#include <maxscale/buffer.h>
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#include <maxscale/protocol.h>
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#include <maxscale/authenticator.h>
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#include <maxscale/ssl.h>
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#include <maxscale/modinfo.h>
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#include <maxscale/poll_core.h>
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#include <netinet/in.h>
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MXS_BEGIN_DECLS
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#define ERRHANDLE
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struct session;
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struct server;
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struct service;
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struct servlistener;
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struct dcb;
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#define DCBFD_CLOSED -1
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/**
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* The statistics gathered on a descriptor control block
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*/
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typedef struct dcbstats
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{
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int n_reads; /*< Number of reads on this descriptor */
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int n_writes; /*< Number of writes on this descriptor */
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int n_accepts; /*< Number of accepts on this descriptor */
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int n_buffered; /*< Number of buffered writes */
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int n_high_water; /*< Number of crosses of high water mark */
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int n_low_water; /*< Number of crosses of low water mark */
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} DCBSTATS;
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#define DCBSTATS_INIT {0}
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/* DCB states */
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typedef enum
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{
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DCB_STATE_UNDEFINED, /*< State variable with no state */
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DCB_STATE_ALLOC, /*< Memory allocated but not populated */
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DCB_STATE_POLLING, /*< Waiting in the poll loop */
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DCB_STATE_WAITING, /*< Client wanting a connection */
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DCB_STATE_LISTENING, /*< The DCB is for a listening socket */
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DCB_STATE_DISCONNECTED, /*< The socket is now closed */
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DCB_STATE_NOPOLLING, /*< Removed from poll mask */
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} dcb_state_t;
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typedef enum
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{
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DCB_ROLE_SERVICE_LISTENER, /*< Receives initial connect requests from clients */
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DCB_ROLE_CLIENT_HANDLER, /*< Serves dedicated client */
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DCB_ROLE_BACKEND_HANDLER, /*< Serves back end connection */
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DCB_ROLE_INTERNAL /*< Internal DCB not connected to the outside */
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} dcb_role_t;
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#define DCB_STRTYPE(dcb) (dcb->dcb_role == DCB_ROLE_CLIENT_HANDLER ? "Client DCB" : \
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dcb->dcb_role == DCB_ROLE_BACKEND_HANDLER ? "Backend DCB" : \
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dcb->dcb_role == DCB_ROLE_SERVICE_LISTENER ? "Listener DCB" : \
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dcb->dcb_role == DCB_ROLE_INTERNAL ? "Internal DCB" : "Unknown DCB")
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/**
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* Callback reasons for the DCB callback mechanism.
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*/
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typedef enum
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{
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DCB_REASON_CLOSE, /*< The DCB is closing */
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DCB_REASON_DRAINED, /*< The write delay queue has drained */
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DCB_REASON_HIGH_WATER, /*< Cross high water mark */
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DCB_REASON_LOW_WATER, /*< Cross low water mark */
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DCB_REASON_ERROR, /*< An error was flagged on the connection */
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DCB_REASON_HUP, /*< A hangup was detected */
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DCB_REASON_NOT_RESPONDING /*< Server connection was lost */
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} DCB_REASON;
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/**
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* Callback structure - used to track callbacks registered on a DCB
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*/
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typedef struct dcb_callback
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{
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DCB_REASON reason; /*< The reason for the callback */
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int (*cb)(struct dcb *dcb, DCB_REASON reason, void *userdata);
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void *userdata; /*< User data to be sent in the callback */
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struct dcb_callback *next; /*< Next callback for this DCB */
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} DCB_CALLBACK;
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/**
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* State of SSL connection
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*/
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typedef enum
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{
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SSL_HANDSHAKE_UNKNOWN, /*< The DCB has unknown SSL status */
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SSL_HANDSHAKE_REQUIRED, /*< SSL handshake is needed */
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SSL_HANDSHAKE_DONE, /*< The SSL handshake completed OK */
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SSL_ESTABLISHED, /*< The SSL connection is in use */
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SSL_HANDSHAKE_FAILED /*< The SSL handshake failed */
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} SSL_STATE;
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/**
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* Descriptor Control Block
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*
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* A wrapper for a network descriptor within the gateway, it contains all the
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* state information necessary to allow for the implementation of the asynchronous
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* operation of the protocol and gateway functions. It also provides links to the service
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* and session data that is required to route the information within the gateway.
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*
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* It is important to hold the state information here such that any thread within the
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* gateway may be selected to execute the required actions when a network event occurs.
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*
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* Note that the first few fields (up to and including "entry_is_ready") must
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* precisely match the LIST_ENTRY structure defined in the list manager.
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*/
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typedef struct dcb
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{
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MXS_POLL_DATA poll;
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skygw_chk_t dcb_chk_top;
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bool dcb_errhandle_called; /*< this can be called only once */
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dcb_role_t dcb_role;
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int fd; /**< The descriptor */
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dcb_state_t state; /**< Current descriptor state */
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SSL_STATE ssl_state; /**< Current state of SSL if in use */
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int flags; /**< DCB flags */
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char *remote; /**< Address of remote end */
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char *user; /**< User name for connection */
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struct sockaddr_storage ip; /**< remote IPv4/IPv6 address */
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char *protoname; /**< Name of the protocol */
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void *protocol; /**< The protocol specific state */
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size_t protocol_packet_length; /**< How long the protocol specific packet is */
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size_t protocol_bytes_processed; /**< How many bytes of a packet have been read */
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struct session *session; /**< The owning session */
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struct servlistener *listener; /**< For a client DCB, the listener data */
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MXS_PROTOCOL func; /**< The protocol functions for this descriptor */
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MXS_AUTHENTICATOR authfunc; /**< The authenticator functions for this descriptor */
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int writeqlen; /**< Current number of byes in the write queue */
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GWBUF *writeq; /**< Write Data Queue */
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GWBUF *delayq; /**< Delay Backend Write Data Queue */
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GWBUF *readq; /**< Read queue for storing incomplete reads */
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GWBUF *fakeq; /**< Fake event queue for generated events */
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uint32_t fake_event; /**< Fake event to be delivered to handler */
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DCBSTATS stats; /**< DCB related statistics */
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struct dcb *nextpersistent; /**< Next DCB in the persistent pool for SERVER */
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time_t persistentstart; /**< 0: Not in the persistent pool.
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-1: Evicted from the persistent pool and being closed.
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non-0: Time when placed in the persistent pool.
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*/
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struct service *service; /**< The related service */
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void *data; /**< Specific client data, shared between DCBs of this session */
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void *authenticator_data; /**< The authenticator data for this DCB */
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DCB_CALLBACK *callbacks; /**< The list of callbacks for the DCB */
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int64_t last_read; /*< Last time the DCB received data */
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struct server *server; /**< The associated backend server */
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SSL* ssl; /*< SSL struct for connection */
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bool ssl_read_want_read; /*< Flag */
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bool ssl_read_want_write; /*< Flag */
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bool ssl_write_want_read; /*< Flag */
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bool ssl_write_want_write; /*< Flag */
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bool was_persistent; /**< Whether this DCB was in the persistent pool */
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struct
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{
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struct dcb *next; /**< Next DCB in owning thread's list */
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struct dcb *tail; /**< Last DCB in owning thread's list */
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} thread;
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uint32_t n_close; /** How many times dcb_close has been called. */
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char *path; /** If a Unix socket, the path it was bound to. */
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skygw_chk_t dcb_chk_tail;
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} DCB;
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/**
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* The DCB usage filer used for returning DCB's in use for a certain reason
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*/
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typedef enum
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{
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DCB_USAGE_CLIENT,
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DCB_USAGE_LISTENER,
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DCB_USAGE_BACKEND,
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DCB_USAGE_INTERNAL,
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DCB_USAGE_ALL
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} DCB_USAGE;
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/* A few useful macros */
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#define DCB_SESSION(x) (x)->session
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#define DCB_PROTOCOL(x, type) (type *)((x)->protocol)
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#define DCB_WRITEQLEN(x) (x)->writeqlen
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#define DCB_SET_LOW_WATER(x, lo) (x)->low_water = (lo);
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#define DCB_SET_HIGH_WATER(x, hi) (x)->low_water = (hi);
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#define DCB_BELOW_LOW_WATER(x) ((x)->low_water && (x)->writeqlen < (x)->low_water)
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#define DCB_ABOVE_HIGH_WATER(x) ((x)->high_water && (x)->writeqlen > (x)->high_water)
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/**
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* @brief DCB system initialization function
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*
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* This function needs to be the first function call into this system.
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*/
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void dcb_global_init();
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int dcb_write(DCB *, GWBUF *);
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DCB *dcb_accept(DCB *listener);
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DCB *dcb_alloc(dcb_role_t, struct servlistener *);
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DCB *dcb_connect(struct server *, struct session *, const char *);
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int dcb_read(DCB *, GWBUF **, int);
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int dcb_drain_writeq(DCB *);
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void dcb_close(DCB *);
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/**
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* @brief Close DCB in the thread that owns it.
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*
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* @param dcb The dcb to be closed.
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*
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* @note Even if the calling thread owns the dcb, the closing will
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* still be made via the event loop.
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*/
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void dcb_close_in_owning_thread(DCB *dcb);
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void printAllDCBs(); /* Debug to print all DCB in the system */
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void printDCB(DCB *); /* Debug print routine */
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void dprintDCBList(DCB *); /* Debug print DCB list statistics */
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void dprintAllDCBs(DCB *); /* Debug to print all DCB in the system */
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void dprintOneDCB(DCB *, DCB *); /* Debug to print one DCB */
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void dprintDCB(DCB *, DCB *); /* Debug to print a DCB in the system */
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void dListDCBs(DCB *); /* List all DCBs in the system */
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void dListClients(DCB *); /* List al the client DCBs */
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const char *gw_dcb_state2string(dcb_state_t); /* DCB state to string */
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void dcb_printf(DCB *, const char *, ...) __attribute__((format(printf, 2, 3))); /* DCB version of printf */
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void dcb_hashtable_stats(DCB *, void *); /**< Print statisitics */
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int dcb_add_callback(DCB *, DCB_REASON, int (*)(struct dcb *, DCB_REASON, void *), void *);
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int dcb_remove_callback(DCB *, DCB_REASON, int (*)(struct dcb *, DCB_REASON, void *), void *);
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int dcb_count_by_usage(DCB_USAGE); /* Return counts of DCBs */
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int dcb_persistent_clean_count(DCB *, int, bool); /* Clean persistent and return count */
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void dcb_hangup_foreach (struct server* server);
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uint64_t dcb_get_session_id(DCB* dcb);
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char *dcb_role_name(DCB *); /* Return the name of a role */
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int dcb_accept_SSL(DCB* dcb);
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int dcb_connect_SSL(DCB* dcb);
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int dcb_listen(DCB *listener, const char *config, const char *protocol_name);
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void dcb_enable_session_timeouts();
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void dcb_process_idle_sessions(int thr);
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/**
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* @brief Append a buffer the DCB's readqueue
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*
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* Usually data is stored into the DCB's readqueue when not enough data is
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* available and the processing needs to be deferred until more data is available.
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*
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* @param dcb The DCB to be appended to.
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* @param buffer The buffer to append.
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*/
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static inline void dcb_readq_append(DCB *dcb, GWBUF *buffer)
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{
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dcb->readq = gwbuf_append(dcb->readq, buffer);
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}
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/**
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* @brief Returns the read queue of the DCB.
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*
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* @note The read queue remains the property of the DCB.
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*
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* @return A buffer of NULL if there is no read queue.
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*/
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static GWBUF* dcb_readq_get(DCB* dcb)
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{
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return dcb->readq;
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}
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/**
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* @brief Returns whether a DCB currently has a read queue.
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*
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* @return True, if the DCB has a read queue, otherwise false.
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*/
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static inline bool dcb_readq_has(DCB* dcb)
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{
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return dcb->readq != NULL;
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}
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/**
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* @brief Returns the current length of the read queue
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*
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* @return Length of read queue
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*/
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static unsigned int dcb_readq_length(DCB* dcb)
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{
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return dcb->readq ? gwbuf_length(dcb->readq) : 0;
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}
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/**
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* @brief Prepend a buffer the DCB's readqueue
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*
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* @param dcb The DCB to be prepended to.
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* @param buffer The buffer to prepend
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*/
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static inline void dcb_readq_prepend(DCB *dcb, GWBUF *buffer)
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{
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dcb->readq = gwbuf_append(buffer, dcb->readq);
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}
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/**
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* @brief Returns the read queue of the DCB and sets the read queue to NULL.
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*
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* @note The read queue becomes the property of the caller.
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*
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* @return A buffer of NULL if there is no read queue.
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*/
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static GWBUF* dcb_readq_release(DCB* dcb)
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{
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GWBUF* readq = dcb->readq;
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dcb->readq = NULL;
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return readq;
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}
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/**
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* @brief Set read queue of a DCB
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*
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* The expectation is that there is no readqueue when this is done.
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* The ownership of the provided buffer moved to the DCB.
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*
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* @param dcb The DCB to be reset.
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* @param buffer The buffer to reset with
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*/
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static inline void dcb_readq_set(DCB *dcb, GWBUF *buffer)
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{
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if (dcb->readq)
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{
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MXS_ERROR("Read-queue set when there already is a read-queue.");
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// TODO: Conceptually this should be freed here. However, currently
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// TODO: the code just assigns without checking, so we do the same
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// TODO: for now. If this is not set to NULL when it has been consumed,
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// TODO: we would get a double free.
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// TODO: gwbuf_free(dcb->readq);
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dcb->readq = NULL;
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}
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dcb->readq = buffer;
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}
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/**
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* @brief Call a function for each connected DCB
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*
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* @deprecated You should not use this function, use dcb_foreach_parallel instead
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*
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* @param func Function to call. The function should return @c true to continue iteration
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* and @c false to stop iteration earlier. The first parameter is a DCB and the second
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* is the value of @c data that the user provided.
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* @param data User provided data passed as the second parameter to @c func
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* @return True if all DCBs were iterated, false if the callback returned false
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*/
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bool dcb_foreach(bool (*func)(DCB *dcb, void *data), void *data);
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/**
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* @brief Call a function for each connected DCB
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*
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* @note This function can call @c func from multiple thread at one time.
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*
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* @param func Function to call. The function should return @c true to continue iteration
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* and @c false to stop iteration earlier. The first is a DCB and
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* the second is this thread's value in the @c data array that
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* the user provided.
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*
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* @param data Array of user provided data passed as the second parameter to @c func.
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* The array must have more space for pointers thann the return
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* value of `config_threadcount()`. The value passed to @c func will
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* be the value of the array at the index of the current thread's ID.
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*/
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void dcb_foreach_parallel(bool (*func)(DCB *dcb, void *data), void **data);
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/**
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* @brief Return the port number this DCB is connected to
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*
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* @param dcb DCB to inspect
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* @return Port number the DCB is connected to or -1 if information is not available
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*/
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int dcb_get_port(const DCB *dcb);
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/**
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* @brief Return the DCB currently being handled by the calling thread.
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*
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* @return A DCB, or NULL if the calling thread is not currently handling
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* a DCB or if the calling thread is not a polling/worker thread.
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*/
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DCB* dcb_get_current();
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/**
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* DCB flags values
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*/
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#define DCBF_HUNG 0x0002 /*< Hangup has been dispatched */
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#define DCBF_REPLIED 0x0004 /*< DCB was written to */
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#define DCB_REPLIED(d) ((d)->flags & DCBF_REPLIED)
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MXS_END_DECLS
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