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shmdb

A memory database based on shared memory.

1. can do

shmdb shared memory multi-process aimed at resolving the problem. Under linux or windows, operating system provides a shared memory feature, you can apply for a memory area by calling the system function, shmdb is the use of this feature of the operating system, the framework of a key-value type of database. When used to set up a pair of key-value through the function shmdb_put, also to get a pair of key-value through the function shmdb_get.

2. can not do

shmdb does not provide network access functions can only be embedded into applications to run. It is not suitable for network databases.

3.API

3.1 shmdb_initParent parent process initializes

int shmdb_initParent (STHashShareHandle * handle, unsigned int size)

Parameters

  • [In | out] STHashShareHandle * handle shmid,which is the member variable of handle will ben initialize in this function
  • unsigned int size specified base area
  • [In] STShmdbOption *option the option of log,can be NULL.

The return value

  • int result of the operation

3.2 shmdb_initChild child process initialization

int shmdb_initChild (STHashShareHandle * handle)

Parameters
   

  • [In] STHashShareHandle * handle internal memory function to mount its own memory area based to the shared memory via the handle's shmid
      The return value

  • int result of the operation

3.3 shmdb_put write value

int shmdb_put (STHashShareHandle * handle, const char * key, unsigned short keyLen, 
const char * value, unsigned short valueLen)

Parameters

  • [In] STHashShareHandle * handle internal function to read the value of handle's shmid to manipulate shared memory
  • [In] const char * key
  • unsigned short keyLen
  • [In] const char * value
  • unsigned short valueLen

The return value

  • int result of the operation

3.4 shmdb_get get the value

shmdb_get (STHashShareHandle * handle, const char * key, unsigned short keyLen, 
char ** value, unsigned short * valueLen)

Parameters

  • [In] STHashShareHandle * handle internal function to read the value of handle's shmid to manipulate shared memory
  • [In] const char * key
  • unsigned short keyLen
  • [Out] char ** value internal function allocate the memory space of value, manually call the free function after this call is completed. If valueLen value is NULL, the function does not allocate the space of value.
  • unsigned short * valueLen

The return value

  • int result of the operation

3.5 shmdb_delete delete values

int shmdb_delete (STHashShareHandle * handle, const char * key, unsigned short keyLen, 
char ** value, unsigned short * valueLen)

Parameters

  • [In] STHashShareHandle * handle internal function to read the value of handle's shmid to manipulate shared memory
  • [In] const char * key
  • unsigned short keyLen
  • [Out] char ** value internal function allocate the memory space of value, manually call the free function after this call is completed. If valueLen value is NULL, the function does not allocate the space of value.
  • unsigned short * valueLen

The return value

  • int result of the operation

3.6 shmdb_destroy destruction

When the program exits normally, you should call this function manually to remove the shared memory from the operating system.

int shmdb_destroy (STHashShareHandle * handle)

Parameters

  • [In] STHashShareHandle * handle internal function to read the value of handle's shmid to manipulate shared memory

The return value

  • int result of the operation

Contributors

yunnysunny (maintainer)

License: Apache License, Version 2.0