gsoc:2009:api

Abstract Extension API and Dependency Interface

Details

  • Student: Varuna Jayasiri
  • Mentor: shire
  • Timezone: GMT +5:30 (Varuna)
  • Mailing list: pecl-dev@lists.php.net

Abstract

The objective of this project is to develop functionality for PHP that will allow extensions to register a set of functions as a versioned API, since PHP does not currently handle interdependencies among PHP extensions well, which leads to various problems. This would also solve the current problem of extension load order.

Documentation

Versioning

Versions are in the format major.minor[.build[.revision]] in the string representation. These are stored in unsigned integers for ease of searching. The first 8 bits are used for the major, next 8 for the minor, next 8 for the build and the last 8 bits for the revision. It is possible to convert from the string representation to an unsigned integer using zend_eapi_toi and from an unsigned integer to the string format using zend_eapi_toa function.

Macros

EAPI_SET_CALLBACK(ext_name, version, callback) 

Sets a callback - with reference to a extension and a version - should be called during MINIT. The callback will be called after all extensions have been initialized. Callback will be called with a reference to the API of the specified extension. See zend_eapi_set_callback.

ext_name Extension name
version Version - if a null value will is passed the callback will be called with the latest version
callback Function pointer to the callback function
EAPI_SET_EMPTY_CALLBACK(callback) 

Sets an empty callback - should be called during MINIT. The callback will be called after all extensions have been initialized. See zend_eapi_set_empty_callback.

callback Function pointer to the callback function
EAPI_CALLBACK_FUNCTION(callback) 

Defines the callback function. The callback function will be called with the following parameters: type, module_number, api (pointer to the api), ext_name, version,

callback Name of the callback function
EAPI_EMPTY_CALLBACK_FUNCTION(callback) 

Defines the empty callback function. The callback function will be called with the following parameters: typei and module_number,

callback Name of the callback function

Functions

All functions return SUCCESS on success and FAILURE on failure.

int zend_eapi_register(char *ext_name, char * version_text, void *api, size_t size)

Registers an API

ext_name Extension name
version API version in format major.minor[.build[.revision]]
api A ponter to the API structure
size Size of the API structure
int zend_eapi_version_toi(char *version_text, uint *version_int)

Converts a version in text format to an integer.

version_text Version as a string
version_int Version as a numerical value
int zend_eapi_version_toa(uint version, char * version_text)

Converts a version in integer format to a string

version_text Version as a string
version_int Version as a numerical value
int zend_eapi_find_versions(char *ext_name, uint version, uint mask, uint *result, int *size, int buf_length)

Finds the set of versions available. Matches versions if (extension_version & mask) == (version & mask).

ext_name Extension name
version Version to be searched for
mask A mask to specify which part of version should be matched
result Pointer to an array, which will be filled with matched versions
size Number of matches found
buf_length Capacity of the array results (memory allocated)
int zend_eapi_get_latest_version(char *ext_name, uint *version)

Gives the latest version of the extension available

ext_name Extension name
version Latest version as a numerical value
int zend_eapi_exists(char *ext_name, char *version)

Checks if the API is available

ext_name Extension name
version Version
int zend_eapi_get(char *ext_name, char *version, void **api)

Retrieves the API

ext_name Extension name
version Version
api API will be loaded here if it is available
int zend_eapi_set_empty_callback(int type, int module_number, void (*callback)(EMPTY_CALLBACK_FUNC_ARGS))

Sets an empty callback - should be called during MINIT. The callback will be called after all extensions have been initialized. Use EAPI_SET_EMPTY_CALLBACK.

callback Function pointer to the callback function
int zend_eapi_set_callback(int type, int module_number, char *ext_name, char *version, void (*callback_func)(CALLBACK_FUNC_ARGS))

Sets a callback - with reference to a extension and a version - should be called during MINIT. The callback will be called after all extensions have been initialized. Callback will be called with a reference to the API of the specified extension. Use EAPI_SET_CALLBACK.

ext_name Extension name
version Version - if a null value will is passed the callback will be called with the latest version
callback Function pointer to the callback function

Timeline

20th April to 23rd May – Community bonding period

  • Getting more familiarized with PHP core and Zend
  • Submitting the proposed API and design for suggestions
  • Getting ideas from the developer community on how this should be developed
  • Finalizing the design

23rd May to 1st July – Implementing most important features

  • The API registration and retrieval component will be developed
  • The interface for setting up the callback function will not be implemented at this stage, instead a simpler interface (e.g. php_get_api) would be provided
  • Code written will be unit tested
  • This would be a standard to be distributed for testing

1st July to 10th July – Testing the implemented section

  • The implemented features will be tested with help from the community
  • Any bugs encountered will be fixed
  • Any suggestions for improvements will be considered and implemented

10th July to 1st August – Completing the implementation of all features

  • All the functionality described above will be completed
  • Code written will be unit tested
  • Behavior of the component in various scenarios with interdependencies among extensions, will be tested thoroughly

1st August to 4th August – Buffer

  • Small buffer period so that any additional things that come up in the way could be implemented or if time taken for implementation exceeds time estimated
  • The completed extension API and dependency interface will be made available for the developer community
  • Any improvements suggested will be considered and implemented

4th August to 17th August – Testing

  • Any bug fixes will be implemented
  • All documentations will be completed
  • It will be ready for distribution at the end of testing

Progress

12th May
  • Setup the development environment
  • Working on the GIT repository - git://github.com/vpj/PHP-Extension-API.git
  • Made a few changes to the proposed design
    • All the code will be a part of zend and hence all function will be prefixed with zend_ and not php_
    • Prefixed all the functions with zend_ext_api instead of function names like php_register_api
15th May
  • Discussing how different versions of API's should be maintained
  • Coded the basic functionality
    • Memory leaks and exception handling were not considered (TODO's were added to make sure these will be addressed later)
23rd May
  • Two hashtables are used - one to store the API's and the other to store the available versions
  • A simple list is used to store the set of versions available
  • Versions are represented in major.minor[.build[.revision]] or major.minor[.maintenance[.build]] formats; i.e. “x.x.x.x”
    • These are converted to a 32 bit integer for indexing
    • Bit masks could be used to identify ranges of versions easily
31st May
  • Included a function to get the latest version of an extension available
  • Functions to convert version from major.minor[.build[.revision]] format to an uint and vice versa are provided.
    • when representing the version in uint first 8 bits will be used for major and the next 8 for minor and so on
  • A few memory leaks were fixed
5th June
  • Added some documentation of the interface
  • Did some testing
27th June
  • Coded the callback registration
    • Callbacks are called from php_module_startup (main/main.c)
    • Tested callbacks
    • Update sample usage code
10th July
  • Callbacks
    • Module number is passed to the callback
    • Callbacks can be registered for the latest API version
  • Testing
    • Two extension with a set of standard unit test cases were added to the git repository
    • API interface was tested with the extensions mbstring and exif
  • Name
    • eapi is used instead of ext_api
20th July
  • Callbacks with no extension specified
  • Used dependency interface on mbstring/exif
31st July
16th August
  • Received some suggestions from the community (mailing list)
  • Fixed a problem with win32 build - included zend_eapi.c in config.w32
  • TSRMLS parameters are passed to callbacks to improve performance
  • Added support for extensions loaded through dl()
    • When a extension (say ext_dl) is loaded through dl() the callbacks of other extensions (already loaded) are called, if they require the ext_dl and the versions match
    • Callbacks of ext_dl are called if the required extensions are available
    • Did some testing with dl()
gsoc/2009/api.txt · Last modified: 2011/04/06 12:59 (external edit)