Channels

Detailed Description

Channels are ways of exchanging data between threads. libfsds (Lock Free Data Structures) are used to form channels and exchange transactions or uni-directional messages.

Resource channel(s) are used to notify DNS query processing threads when a resource has changed. Messages are transactional in nature (request-response).

Query log channel is used to notify DNS query aprocessing threads when to flip query log buffers.

Log channel is used to send uni-directional log messages to application logging thread which in turn logs messages to file (disk).

Data Structures
struct	channel_bss_msg_s
struct	channel_bss_queue_s
struct	channel_bss_s
struct	channel_log_msg_s
struct	channel_log_s

Typedefs
typedef enum channel_bss_ops_e	channel_bss_ops_t
typedef struct channel_bss_msg_s	channel_bss_msg_t
typedef struct channel_bss_queue_s	channel_bss_queue_t
typedef struct channel_bss_s	channel_bss_t
typedef struct channel_log_msg_s	channel_log_msg_t
typedef struct channel_log_s	channel_log_t

Enumerations
enum	channel_bss_ops_e { CH_OP_RES_SET_RESOURCE1 = 0 , CH_OP_RES_SET_RESOURCE2 , CH_OP_QUERY_LOG_FLIP }

Functions
channel_bss_msg_t *	channel_bss_msg_create (uint64_t id, channel_bss_ops_t op, void *p)
void	channel_bss_msg_release (channel_bss_msg_t *msg)
int	channel_bss_send (channel_bss_t *ch, channel_bss_msg_t *msg)
int	channel_bss_recv (channel_bss_t *ch, channel_bss_msg_t **msg)
int	channel_bssvl_send (channel_bss_t *ch, channel_bss_msg_t *msg)
int	channel_bssvl_recv (channel_bss_t *ch, channel_bss_msg_t **msg)
uint64_t	channel_bss_assign_msg_id (uint64_t *id_base)
channel_log_msg_t *	channel_log_msg_create (uint32_t log_msg_id, char *log_msg, bool exit)
void	channel_log_msg_release (channel_log_msg_t *msg)
int	channel_log_send (channel_log_t *ch, channel_log_msg_t *msg)
int	channel_log_recv (channel_log_t *ch, channel_log_msg_t **msg)

Typedef Documentation

channel_bss_msg_t

typedef struct channel_bss_msg_s channel_bss_msg_t

Structure describes an bss channel message.

channel_bss_ops_t

typedef enum channel_bss_ops_e channel_bss_ops_t

Enumerated bss channel operation codes.

channel_bss_queue_t

typedef struct channel_bss_queue_s channel_bss_queue_t

Structure describes an bss bonded channel queue.

channel_bss_t

typedef struct channel_bss_s channel_bss_t

Structure describes an bss channel, Channel has two queues. Each queue is unidirectional.

channel_log_msg_t

typedef struct channel_log_msg_s channel_log_msg_t

Structure describes a log channel message.

channel_log_t

typedef struct channel_log_s channel_log_t

Structure describes a log channel.

Enumeration Type Documentation

channel_bss_ops_e

enum channel_bss_ops_e

Enumerated bss channel operation codes.

Enumerator
CH_OP_RES_SET_RESOURCE1	Op code for resource 1.
CH_OP_RES_SET_RESOURCE2	Op code for resource 2.
CH_OP_QUERY_LOG_FLIP	Op code for query log flip.

Function Documentation

channel_bss_assign_msg_id()

uint64_t channel_bss_assign_msg_id

(

uint64_t *

id_base

)

Assign a new channel message ID from given base.

Base is incremented and value returned.

Parameters

id_base

Returns

uint64_t

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channel_bss_msg_create()

channel_bss_msg_t * channel_bss_msg_create	(	uint64_t	id,
		channel_bss_ops_t	op,
		void *	p
	)

Create a bss channel message object.

Parameters

id	Message ID
op	Message operation, see channel_bss_ops_t.
p	Pointer to data this message applies to.

Returns

On success returns pointer to newly created message. Caller is responsible for releasing the message via channel_bss_msg_release once message is no longer needed.

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channel_bss_msg_release()

void channel_bss_msg_release

(

channel_bss_msg_t *

msg

)

Release (free memory) a bss message object.

Parameters

msg	Message to release.

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channel_bss_recv()

int channel_bss_recv	(	channel_bss_t *	ch,
		channel_bss_msg_t **	msg
	)

Receive a message from support (bss) part of the channel.

This is used by vectorloop threads to receive message from support thread.

Parameters

ch	Channel to receive message on.
msg	Pointer where to place the received message.

Returns

On success returns 1, otherwise returns 0. 0 could only be returned if there are no messages in the channel.

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channel_bss_send()

int channel_bss_send	(	channel_bss_t *	ch,
		channel_bss_msg_t *	msg
	)

Send a message on bss part of the channel.

This is used by support (bss) threads to send message to vectorloop thread.

Parameters

ch	Channel to send message on.
msg	Message to send.

Returns

On success returns 1, otherwise returns 0. 0 could only be returned if message could not be enqueued due channel being full.

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channel_bssvl_recv()

int channel_bssvl_recv	(	channel_bss_t *	ch,
		channel_bss_msg_t **	msg
	)

Receive a message from vectorloop part of the channel.

This is used by support (bss) thread to receive message from vectorloop thread.

Parameters

ch	Channel to receive message on.
msg	Pointer where to place the received message.

Returns

On success returns 1, otherwise returns 0. 0 could only be returned if there are no messages in the channel.

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channel_bssvl_send()

int channel_bssvl_send	(	channel_bss_t *	ch,
		channel_bss_msg_t *	msg
	)

Send a message on vectorloop part of the channel.

This is used by vectorloop thread to send message to support (bss) thread.

Parameters

ch	Channel to send message on.
msg	Message to send.

Returns

On success returns 1, otherwise returns 0. 0 could only be returned if message could not be enqueued due channel being full.

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channel_log_msg_create()

channel_log_msg_t * channel_log_msg_create	(	uint32_t	log_msg_id,
		char *	log_msg,
		bool	exit
	)

Create a new log channel message object.

Parameters

log_msg_id	Log message ID, see app_log_msg_id_t.
log_msg	Log message string, can be NULL.
exit	Is this a fatal message, meaning should the application exit once message is logged.

Returns

On success returns pointer to newly created message. Caller is responsible for releasing the message via channel_log_msg_release once message is no longer needed.

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channel_log_msg_release()

void channel_log_msg_release

(

channel_log_msg_t *

msg

)

Release (free memory) a log channel message object.

Parameters

msg	Message object to release.

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channel_log_recv()

int channel_log_recv	(	channel_log_t *	ch,
		channel_log_msg_t **	msg
	)

Receive a message from log channel.

This is used by log thread to receive message from other thread.

Parameters

ch	Channel to receive message on.
msg	Pointer where to place the received message.

Returns

On success returns 1, otherwise returns 0. 0 could only be returned if there are no messages in the channel.

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channel_log_send()

int channel_log_send	(	channel_log_t *	ch,
		channel_log_msg_t *	msg
	)

Send a message on log channel.

This is used by threads threads to send message to log thread.

Parameters

ch	Channel to send message on.
msg	Message to send.

Returns

On success returns 1, otherwise returns 0. 0 could only be returned if message could not be enqueued due channel being full.

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