interprocess_buffer.h File Reference
SNMP statistic module, interprocess buffer. More...
#include "../../str.h"
#include "../../locking.h"
#include "snmpstats_globals.h"
#include "hashTable.h"
#include "../usrloc/ucontact.h"
Go to the source code of this file.
Data Structures | |
| struct | interprocessBuffer |
Typedefs | |
| typedef struct interprocessBuffer | interprocessBuffer_t |
Functions | |
| void | consumeInterprocessBuffer (void) |
| void | freeInterprocessBuffer (void) |
| void | handleContactCallbacks (ucontact_t *contactInfo, int type, void *param) |
| int | initInterprocessBuffers (void) |
Variables | |
| interprocessBuffer_t * | endRegUserTableBuffer |
| interprocessBuffer_t * | frontRegUserTableBuffer |
| hashSlot_t * | hashTable |
| gen_lock_t * | interprocessCBLock |
Detailed Description
SNMP statistic module, interprocess buffer.The SNMPStats module exposes user information through openserSIPRegUserTable, openserSIPContactTable, and openserSIPRegUserLookupTable. These tables are populated through callback mechanisms from the usrloc module. Unfortunately the NetSNMP table population code is very slow when dealing with large amounts of data. Because we don't want to experience a performance hit when registering users, we make use of the interprocess buffer. Specifically, instead of adding/removing users/contacts from the SNMP tables directly, the callbacks add an add/delete command to the interprocessBuffer.
When an snmp request is recieved by the SNMPStats sub-process, it will consume this interprocess buffer, adding and deleting users. When it is finished, it can service the SNMP request.
This doesn't remove the NetSNMP inefficiency of course, but it does move it to a non-critical path. Such an approach allows SNMP support with almost no overhead to the rest of the server.
Definition in file interprocess_buffer.h.
Typedef Documentation
| typedef struct interprocessBuffer interprocessBuffer_t |
Function Documentation
| void consumeInterprocessBuffer | ( | void | ) |
Interprocess Buffer consumption Function. This function will iterate over every element of the interprocess buffer, and add or remove the specified contacts and users. Whether the contacts are added or removed is dependent on if the original element was added as a result of a UL_CONTACT_INSERT or UL_CONTACT_EXPIRE callback.
The function will free any memory occupied by the interprocess buffer.
- Note:
- This function is believed to be thread safe. Specifically, it protects corruption of the interprocess buffer through the interprocessCBLock. This ensures no corruption of the buffer by race conditions. The lock has been designed to be occupied for as short a period as possible, so as to prevent long waits. Specifically, once we start consumption of the list, other processes are free to continue even before we are done. This is made possible by simply changing the head of the interprocess buffer, and then releasing the lock.
Definition at line 208 of file interprocess_buffer.c.
References executeInterprocessBufferCmd(), interprocessCBLock, interprocessBuffer::next, NULL, shm_free, interprocessBuffer::stringContact, and interprocessBuffer::stringName.
Referenced by openserSIPContactTable_get_value(), openserSIPRegUserLookupTable_set_action(), and openserSIPRegUserTable_get_value().
| void freeInterprocessBuffer | ( | void | ) |
Definition at line 350 of file interprocess_buffer.c.
References LM_DBG, interprocessBuffer::next, NULL, shm_free, interprocessBuffer::stringContact, and interprocessBuffer::stringName.
Referenced by mod_destroy().
| void handleContactCallbacks | ( | ucontact_t * | contactInfo, | |
| int | type, | |||
| void * | param | |||
| ) |
USRLOC Callback Handler:
This function should be registered to receive callbacks from the usrloc module. It can be called for any of the callbacks listed in ul_callback.h. The callback type will be passed in 'type', and the contact the callback applies to will be supplied in 'contactInfo. This information will be copied into the interprocess buffer. The interprocess buffer will be consumed at a later time, when consumeInterprocessBuffer() is called.
This callback is thread safe with respect to the consumeInterprocessBuffer() function. Specifically, the interprocess buffer should not be corrupted by any race conditions between this function and the consumeInterprocessBuffer() function.
Definition at line 136 of file interprocess_buffer.c.
References ucontact::aor, ucontact::c, interprocessBuffer::callbackType, interprocessBuffer::contactInfo, convertStrToCharString(), interprocessCBLock, LM_ERR, interprocessBuffer::next, NULL, _str::s, shm_malloc(), interprocessBuffer::stringContact, and interprocessBuffer::stringName.
Referenced by registerForUSRLOCCallbacks().
| int initInterprocessBuffers | ( | void | ) |
Initialize shared memory used to buffer communication between the usrloc module and the SNMPStats module. (Specifically, the user and contact tables)
Definition at line 85 of file interprocess_buffer.c.
References createHashTable(), HASH_SIZE, interprocessCBLock, LM_ERR, NULL, shm_free, and shm_malloc().
Referenced by mod_init().
Variable Documentation
Definition at line 68 of file interprocess_buffer.c.
All interprocess communication is stored between these two declarations.
Definition at line 67 of file interprocess_buffer.c.
The hash table:
1) maps all aor's to snmp's UserIndex for help in deleting SNMP Rows.
2) maps a given aor to a contact list.
Definition at line 64 of file interprocess_buffer.c.
Referenced by createHashTable(), openserSIPRegUserLookupTable_set_action(), and updateUser().
| gen_lock_t* interprocessCBLock |
This is to protect the potential racecondition in which a command is added to the buffer while it is being consumed
Definition at line 72 of file interprocess_buffer.c.
Referenced by consumeInterprocessBuffer(), handleContactCallbacks(), and initInterprocessBuffers().
