2. Congratulations!
• You’ve decided to learn “down the stack”
• You’ll learn more than you do “across the stack”
• Your brain will hurt a bit
• This will require you to be involved in your own learning
process
• It is HARDWORK to be good at anything new
7. But I don’t know C!
1. compiled
2. strictly typed
3. php internals do “hard” stuff
4. copy and paste! boilerplate and macros
5. cairo, pecl_http, date
6. Don’t do the hard stuff first!
https://lxr.php.net
11. Quick Setup Needs
1. compiler
2. sdk
3. tools
4. dependencies
5. code
phpize is your friend!
12. How to Compile an Extension
1. phpize
2. ./configure
3. make
4. make install
5. make test
configure might require –with-php-config=/path/to/something
but…
13. But wait – there’s more!
• Compile your own PHP source, use a –prefix
• /usr/local/php-7.0-debug-zts is one I use
• I also have 20 php’s installed
• We want developer specific flags
• --enable-maintainer-zts and --enable-debug
• optionally –enable-gcov
• install gdb and valgrind and optionally lcov
• this is easy on Ubuntu and similar systems where packages are easy to get
• You can also compile php with clang instead of gcc and do things like use static
analysis
14. Rasmus to the Rescue!
• https://github.com/rlerdorf/php7dev/blob/master/README.md
tl;dr
1. install virtualbox
2. install vagrant
3. git clone https://github.com/rlerdorf/php7dev.git
4. cd php7dev
5. vagrant up
6. vagrant ssh
7. makephp 7
15. How to Play along
git clone https://github.com/auroraeosrose/php-extensions-code.git
git checkout scaffolding
phpize
./configure
make
make test
17. 1. Set up compile environment
2. Write a module definition
3. Learn about the PHP lifecycle
4. Learn about zvals
5. Add functions
6. ???
7. Profit!
Every Other ExtensionsTalk
20. 1. Do something you can’t do in userland
2. Utilize a C library
3. Make slow code faster
Maybe you should just use ffi!
Step 1. Why?
21. What is FFI?
• Foreign function interface
• Java calls it JNI
• HHVM calls it HNI
• Python calls it “ctypes” (do not ask, stupidest name ever)
• C# calls it P/Invoke
• Ruby calls it FFI
• PHP calls it…
23. Oh wait…
• php’s ffi is rather broken (last release is 2004-01-20)
• php’s ffi has no maintainer (ilia and wez were doing it)
• It needs someTLC
• There’s MFFI but it’s not done
• https://github.com/mgdm/MFFI
• Are you interested and not afraid? See me!
24. 1. I hate parsing URIs
2. PHP’s parse_url is… not the best
3. How about an extension that wraps something
that parses uris in an excellent fashion
4. RESEARCHTIME
Step 2.What
26. C library to the rescue!
• uriparser.sourceforge.net
• strictly RFC 3986 compliant
• available on many systems as packages
• cross platform
• documented http://uriparser.sourceforge.net/doc/html/
27. 1. Think about what the API should be
2. Look at the C APIs but don’t mimic them
3. Write an example of how youWANT it to work
4. Write more then one example!
5. Turn these examples into your first tests
6. Yes this isTDD
Step 3. How
28.
29. 1. This is copy and paste
1. config.m4 & config.w32
2. macros for version api changes if necessary
3. main module file (php_{$ext}.c)
4. main header file (php_{$ext}.h)
2. Compile it and test!
Step 6. Extension Scaffolding
32. A word about macros
• Preprocessor directives are lines included in a program that
being with the character #, which make them different from a
typical source code text.They are invoked by the compiler to
process some programs before compilation.
• A macro is a fragment of code which has been given a name.
Whenever the name is used, it is replaced by the contents of
the macro.
33. PHP internals is Macro heaven!
• Or hell
• Use http://lxr.php.net to stay sane
34. Scaffolding rules
1. make sure you name your files in a standard way
2. document! use a license header, proto statements
3. read the coding standards http://lxr.php.net/xref/PHP-
MASTER/CODING_STANDARDS
4. FOLLOWTHE CODING STANDARDS
5. use version control early on – github is easy!
35. php –d extension=myext.so –m
The scaffold extension should show up in the list
Make sure to
1. define a version constant
2. read and use PHP code standards
Check if it works
36. 1. run-test.php
2. make test will magically have output
more at http://qa.php.net/write-test.php and docs at
http://qa.php.net/phpt_details.php
Step 7.Write the test
40. Typing systems compared
StaticTyping (C)
• Variables must be declared
before use
• Variables must be given a type at
declaration
• “compile time” checking
DynamicTyping (PHP)
• Variables don’t have to be
declared before use
• Variables can change types
• “run time” checking
43. For more on the new zval
https://nikic.github.io/2015/05/05/Internal-value-representation-in-
PHP-7-part-1.html
44. long any numeric
double numeric with decimal
char* +
size_t
(length)
strings, binary
Hashtable dictionaries, arrays,structs
object any complicated type
45. For more on the new string type
http://jpauli.github.io/2015/09/18/php-string-management.html
46. How do I get C types from a ZVAL?
Z_LVAL(zval) Z_LVAL_P(zval_p) Z_LVAL_PP(zval_pp)
Z_BVAL(zval) Z_BVAL_P(zval_p) Z_BVAL_PP(zval_pp)
Z_DVAL(zval) Z_DVAL_P(zval_p) Z_DVAL_PP(zval_pp)
Z_STRVAL(zval) Z_STRVAL_P(zval_p) Z_STRVAL_PP(zval_pp)
Z_STRLEN(zval) Z_STRLEN_P(zval_p) Z_STRLEN_PP(zval_pp)
Z_ARRVAL(zval) Z_ARRVAL_P(zval_p) Z_ARRVAL_PP(zval_pp)
Z_OBJ(zval) Z_OBJ_P(zval_p) Z_OBJVAL_PP(zval_pp)
Z_OBJ_HANDLE(zval) Z_OBJ_HANDLE_P(zval_p) Z_OBJ_HANDLE_PP(zval_pp)
Z_OBJ_HT(zval) Z_OBJ_HT_P(zval_p) Z_OBJ_HT_PP(zval_pp)
Z_OBJCE(zval) Z_OBJCE_P(zval_p) Z_OBJCE_PP(zval_pp)
Z_OBJPROP(zval) Z_OBJPROP_P(zval_p) Z_OBJPROP_PP(zval_pp)
Z_TYPE(zval) Z_TYPE_P(zval_p) Z_TYPE_PP(zval_pp)
48. 1. tell it to link to ourC library
2. add a function
3. learn how to get data
4. learn how to return data
Step 8. Actually do something
49. I hate autotools…
• Also known as the gnu build system
• provider of much pain, but much good use as well
• autoconf – generates a configure script (we cheat with phpize on shared
extensions)
• makes a configure we run to set up our information, mainly a config.h file
• automake – creates makefiles
• libtool – creates static and dynamic libraries
• Windows? Well php wrote it’s own version of autotools – in jscript (windows
javascript variant)
51. Wait – what was that?
• Define your function in C
• use a special call to parse parameters passed by the user
• use a special zval to return data to the user
• Tell PHP your extension provides this function
• put it in your “giant struct of doom” that lists them all
• send it to php when in your module struct
• Tell PHP what arguments your extension provides
• If your argument information and zpp argue users will be angry
• Yes it sucks you can’t just do one
52. php type code
c type
array or object a zval *
boolean b zend_bool
class C zend_class_entry *
double d double
callable f zend_fcall_info andzend_fcall_info_cache
array or HASH_OF(object) H HashTable*
array h HashTable*
integer l zend_long
integer L zend_long with LONG_MAX, LONG_MIN limits
object o zval *
object of specific type O zval *, zend_class_entry
string (no null bytes) p char*, size_t
resource r zval *
string (possible null bytes) s char*, size_t
actual zval z zval *
actual zval Z zval**
53. zend_parse_parameters
type code
variable args (any) * int, zval**
variable args (1 or more) + int, zval**
| anything after is optional, use defaults
/ use SEPARATE_ZVAL_IF_NOT_REF
doesn’t apply to b, l, and d ! C NULL for zval null
58. Classes
1. name, parent, and flags
2. hashtables of methods, default methods, static
methods
3. hashtables of static properties, default properties,
and properties
4. object handlers
5. union of either file information, or internal
structures (for internal classes)
63. Lifecycle
PHP stops
MSHUTDOWN – for each extension
RSHUTDOWN – for each request
cleanup after test.php
RINIT – for each request
execute test.php
MINIT – for each extension
request/parse test.php
PHP starts
php test.php
64. LifecycleThreaded
PHP stops
MSHUTDOWN – for each extension
request index.php request foo.php
RINIT – for each request
• execute test.php
RSHUTDOWN – for each request
• cleanup after test.php
RINIT – for each request
• execute test.php
RSHUTDOWN – for each request
• cleanup after test.php
MINIT – for each extension
apache starts
76. 1. in your header – use
ZEND_BEGIN|END_MODULE_GLOBALS
2. create the global access macro in your header
(copy and paste)
3. ZEND_DECLARE_MODULE_GLOBALS in every
file where you will use them
4. use the macro to access
COUNTER_G(basic_counter_value)); }
5. Create ginit/gshutdown functions if your globals
need initializing , etc
GlobalVariables (threads = evil)
77. emalloc( )
• allocates the specified number of bytes
safe_emalloc()
• like emalloc but adds a special protection against overflows
efree( )
• releases the specified block of memory back to the system
estrdup( )
• allocate a buffer and copy the string into that buffer
estrndup( )
• same as estrdup when you already know the length of the string
ecalloc( )
• allocates the number of bytes and initializes them to zero
erealloc( )
• resizes the specified block of memory
https://wiki.php.net/internals/zend_mm
78. 1. clean up what you emalloc (C level destructor)
2. read wiki on how to make them extendable!
I mentor PHP developers into becoming C developers – because other PHP devs have done that for me
If you want to move on and do more with extensions after this talk please talk to me – I also sit on freenode all day and answer questions and give feedback – always always want more code monkeys and fresh blood in any project
and looking at extensions makes me sad – 99% suck
Give my short talk about why learning “down the stack” is so important and why more
developers need to stop asking should I learn python or perl
it’s better to learn in a domain entirely different than what you are currently doing
if you do desktop learn web, if you learn web do desktop or mobile
if you do PHP, don’t learn “across” (perl, python, ruby) learn DOWN
java, C#, go, rust
obj-c, C, c++
assembler
the old gurus of C who built what we play with are dying off (do the math, how old is rasmus?)
there won’t be hand holding, but a good mentor (for now me) will help you learn what you need to know
PHP 7 will be breaking all the rules here, changing things in a fundamental manner, just something to keep in mind
We’re working on a project to make migrating to PHP7 well documented and easy when the time comes
and also working on ways to improve extensions in general
This is the reason we have PHP extensions
to hit the lower level parts of the code that are so important
But the top reason is the #1 reason we write PHP extensions
This is usually the first thing people think of when they want to “get involved with PHP internals”
But you will have a far easier time of things if you start with extensions
This is the proper path to get involved in PHP and the language - learning each piece of the stack step by step will
make you not only a better program, and understand the language
but it will make you a better part of the community
This is the #1 argument I hear – but really is not anything you need to worry about
c98 people! you can use some c99 stuff but declarations MUST go at the top of blocks (that’s really good coding standards anyway)
although this will be moot when Microsoft finally gets it’s CTP for 2015
just like php itself turn all your errors on when compiling (-wall is your friend) and try to code clean
you don’t have to “know C” anymore then you have to “know PHP” to write a wordpress plugin
if you have the very basics of what to do it’s not hard
PHP takes care of a lot of the heavy lifting – from how to parse parameters coming in and how to shove data into someplace going out…
to how to do fancy objects
Unless you’re doing something REALLY evil (an opcode cache, changing the way the engine works, threading) most of this stuff has already been done for another extension, it’s just a matter of finding the code – compile and test
btw, all the code generators out there currently suck – most don’t do test generation, doc generation, or use the proper apis
This is the book you want
it’s affectionately called the C bible
if you walk through this book and do the exercise you’ll get the basics of C
These are some pretty good free resources for learning C – walking through the two books and the online tutorial will get you a good portion of the way there
remember programming is thinking as much as writing code
as if you play piano or dance you must practice practice practice
So you’ll need to actually have an environment set up to compile PHP on
I will say right now for your first foray into extensions you will be happiest on linux
a VM is fine, in a debian/ubuntuish flavor because you’ll get a lot more help and support
Also programming for windows and OSX is something you’ll need to learn before you finalize that extension but are much
harder (yes, even OSX is harder – to do it right on there you use homebrew or something similar to install a linux stack –
would be easier at first just to set up a linux vm)
This is the same and yet different on every system and we’re not going to go into it a whole lot – this should have been homework before you came ;)
Basically you need a compiler – xcode on mac, vc(2008) express on windows, gcc something on linux – this is different for every system
You also need the sdk and headers for your system – those will be put on with xcode, you’ll need the 6.1 windows sdk for windows
Then you need autotools – bison, and re2c to build PHP
On mac or linux you can use phpize to build extensions – You CAN do this on windows as well except that for some stupid reason the proper files are not shipped with windows binary builds (stupid)
Then you need any depedencies (to build PHP as a base you need iconv, zlib, and libxml2 at a bare minimum)
After you build PHP on windows you can use phpize (it will be generated for you) and makes life so much easier
make a note that windows does not need the ./ before configure and uses nmake instead of make (otherwise identical)
Note that to use a specific PHP install use /full/path/to/phpize and –with-php-config=/usr/local/php5/bin/php-config
Note this does shared extensions only – then again most of the extensions you’ll work on should probably be shared
So although I wont’ whine about it today – if you really want to do extensions properly you need to have your own php compile
you need to not be afraid of gcc and clang
you need to make sure you test and test and test
There, now we’ve switched to using a precompiled debug zts version of php 7.0
WOOHOO
There aren’t (yet) other box versions/providers available – this is ongoing work (more on gophp7-ext later)
I’m putting parts of this code onto my github account – each section I talk about – scaffolding, adding a function, ext, will have a different branch – feel free to clone and play
These aren’t necessarily complicated extensions but they do follow PHP CS, have all the copy and paste you need and do compile (I think)
So the part we’re all excited about – let’s write an extension! I’ll just get some code and then you copy and compile it and then…
If you’ve ever seen another PHP extensions talk they dive into how to use the zend engine and how things work and such
PHP is to C as wordpress is to PHP – makes any idiot able to write a plugin for it ;)
you don’t necessarily HAVE to know how the internals work – you just have to know the right calls to make!
So although I might tell you about SOME of the internals how and why, for the most part this will be “how to do it” not “why you do it”
Because PHP is a ball of rusty nails ;)
In addition this is the absolutely wrong way to approach writing PHP extensions!
Actually it’s the wrong way to approach writing LOTS of things
do you start out writing a website worrying about how to make a db connection before you’ve designed the database and created the schema? do you create the schema before you have wireframes? just because we’re making a product in a different language doesn’t mean the rules change
this is why you really need to think about what you’re doing – being able to use the extension is not really enough… just wrapping a C api is a good way to give yourselves headaches of a horrible nature
Please be the solution, not the problem
We need no more painful APIs in PHP
so these are the reasons you’d write a PHP extension as we talked about before – you want to use a C library, you want to make something process intensive faster, you want to hook into the engine itself
there aren’t other reasons to do an extension
wait? what is FFI?
So many languages support this idea of calling into usually C code
Then they usually put a layer of regular code “on top” to make APIS non painful
This can be useful
it also tends to be slower
before you get into extension writing – if you just want an ffi wrapper and are just going to call the exact C calls from an existing library why go to the trouble of writing an extension?
ffi is pretty great but a bit of a flakey extension yet, but it’s identical to python’s “ctypes” which is a stupid name, it’s really ffi
I hear al lthe time about how “great” python is because of ctypes, frankly I beg to differ. Part of wrappign a C extension is translating the C calls into something far more “phpish”
oh ffi is cool and so needs a maintainer
so this is what we want to do – write an extension that wraps a good C uri parsing library
so you need to do your research right? there are multiple C parsing libraries, joyent has one and there are some nice c++ ones, but for simple
well laid out C uriparser seems to win – also it’s really nice
use your internet tools – when you started PHP I’m sure you had books and stuff on speed dial
you will need to do the same for C
SO this is a VERY nice C library for parsing uris according to the spec – USEFUL AS ALL GETOUT
cross platform, well maintained, easy to use – don’t let the sourceforge URL fool you, it’s in git
C++ APIs or similar wrappers in python, perl, ruby, etc are a better place to look for api ideas – try a couple of ways of using the apis as well
really think about what kinds of apis and code you’re looking for – so I was looking at wrapping a small library (uriparser.sourceforge.net) and one of the things I did first was sit down and write some rough almost pseudo-code of what the extension might look like
uriparser.sourceforge.net – a simple uri parser library that strictly conforms to rfc
questions to ask yourself as you write these examples
do I want namespaces?
will this be an object oriented api or a procedural style api?
do I want to do the extra work of a dual api? (such as date or mysqli?)
these decisions are usually pretty easy to figure out once you actually try to write the kind of code you want to work
PHP is 90% copy and paste, the main copy and paste stuff is all scaffolding for an extension
so we’ve figure out what we want to write and how we want to write it, now we need to have scaffolding in place for it
talk about our 4 files, the scaffold example - show the files quickly to show what normally goes in a header, some PHP CS rules, et al
DO BOTH unless you’re absolutely certain that whatever you’re writing will only work on one system or the other
m4 is autotools stuff, but the w32 are very easy to write as well, they’re just jscript (windows javascript dialect) with some special functions
for things like checking headers and adding libs, etc
talk about with vs. enable
this is the very basic items you can have in your struct to define what you module is and what it does
STANDARD_MODULE_HEADER_EX allows you to add ini entries and depedencies to your module definition
using STANDARD_MODULE_PROPERTIES_EX allows you to add globals
what the globals are, a ginit and a gshutdown – plus a “post deactivate” method that basically never gets used ;)
Explain what these are to the C uniunitiated
Just some general rules for you to take a look at
even if your extension is not going into PHP proper the more time you take to properly document your code the happier you will be
how to see if what you’ve been playing with will actually work
This should load your boring extension without doing anything fancy, just allow it to show up in the modules list
you can actually do a test case for this with extension_loaded or get_loaded_modules if you’re so inclined
everybody should ALWAYS test their extensions – test test test
turn debugging on, turn memory leaks on - run your tests
if they fail you’ll get a bunch of extra files from the tests system available that make things very easy to debug, a diff file, .out file, even an .sh
file to run the test exactly like it was run the first time
no .bat file yet… yes I have a patch for that
These are very basic functional style tests
there are a bunch of different sections for each one – the important thing to remember is
always include a skipif
anything in “tests” will be run so it’s ok to put things in directories for order
write tests for everything you can think of! this is my standard test to check my phpinfo (MINFO) function
Look at the code and look at the compile
NOTE: again there were many underlying changes made to php’s zvals for php 7
I’m not going to go into all the changes but I may mention a few
we’re going to detour just a moment to learn something about PHP’s guts
But wait – PHP is sitting on C
we are somehow translating C types to PHP types – how is this magic accomplished?
Our zval is a giant struct of doom
for those of you who don’t know what a union is,
A union, is a collection of variables of different types, just like a structure. However, with unions, you can only store information in one field at any one time. You can picture a union as like a chunk of memory that is used to store variables of different types. Once a new value is assigned to a field, the existing data is wiped over with the new data.
This is what everything you do in C goes into!
PHP 7 has totally flipped around how a zval is structured
PHP 7 has totally flipped around how a zval is structured
Simple values do not require allocation and don’t use refcounting.
There is no more double refcounting. In the object case, only the refcount in the object is used now.
Because the refcount is now stored in the value itself, the value can be shared independently of the zval structure. A string can be used both in a zval and a hashtable key.
There is a lot less indirection, i.e. the number of pointers you need to follow to get to a value is lower.
Discuss heap vs. stack memory here
So basically with an extension (especially one wrapping a library) what you’re doing
is taking C variables and exposing them to php land by turning them into zvals
so a “zval” in PHP has a union that can have the value of what is inside – something you’ll need to do when you create your extension is figure out how to “translate” that to a PHP type and how to handle it
In C, strings are simple NULL-terminated char arrays, like you know. However, when designing a scripting language such as PHP, the need to manage those strings arises. In management, we think about classical operations, such as concatenation, extension or truncation ; and eventually more advanced concepts, such as special allocation mechanisms, string interning or string compression.
As length are typed on a size_t variable, they weight {platform size} bytes ! Whatever the platform. One of the PHP 5 problems is then solved : under a CPU64, string length will be 8 bytes (64 digits) for every platform (this is one of the definition of the C size_t type).
Strings are refcounted ! In PHP 7, strings are refcounted (as well as many other primitive types). That means that interned strings are still relevant, but less : PHP layers can now pass strings from one to the other, as strings are refcounted, we are plainly sure that noone will accidentaly free the string as this latter is still used elsewhere (until doing an error on purpose).
p is for pointer (that’s good enough for me)
these are helper macros to get the data OUT of that union of doom that you need, it’s also how you get zval types and other fun stuff
note there are even MORE then this, but these are the ones you’ll use most often
PHP is governed by macros and more macros, which is why it’s important to look at existing PHP extensions since 95% of the macros are NOT documented
The PP macros have been ripped out of php7 because we no longer have pointer pointers all over the place
And the macros without the pointer are used a LOT more than they used to be
Booleans have internally changed – you should always check for IS_FALSE and IS_TRUE instead of considering as a Boolean value, and doing an lval on it will break
Now let’s make our extension like… actually do something
So we’re going to actually write a function for our uriparser library that does something extremely simple – we’re going to register a function to tell us the uriparser library version
Here show all the lines required to do one thing – link into the library
mention how other options are thin on the ground, although cmake is gainin some major traction
about 2008 there was an attempt to port php’s build system to cmake
sadly cmake was not really ready for it
it IS ready for it now (hhvm and others all use cmake)
But again that’s a monstrous project and you’re fighting a battle
gains? one build system for everything ,not maintaining our own configure system for windows, easier integration into ecosystems
you need to do three things to add a function to your extension
define it’s arguments – this is for reflection
define it’s body
put it inside a function struct
arginfo must have the begin and end arginfo
then you add additional arguments as desired in between
if you have optional arguments, use begin_arginfo_ex
you can send by val or reference or do typehinting with arginfo as well
SO a lot of this is implementation detail issues
so in PHP you use this macro – all it does is rename your function name to something that won’t collide evilly, and define a bunch
of C parameters you’re getting passed in
there are even more than this
in php7 strings move to use the more correct
The IS_LONG type now uses a zend_long value instead of an ordinary C long. The reason behind this is that on 64-bit Windows (LLP64) a long is only 32-bit wide, so PHP 5 ended up always using 32-bit numbers on Windows. PHP 7 will allow you to use 64-bit numbers if you’re on an 64-bit operating system, even if that operating system is Windows.
so you can also do “zend_parse_parameters_ex” the only thing you can do it with is QUIET
there are a couple of reasons for doing this – mostly nesting and overloaded calls
Note that variable args have dropped a pointer!
This is macro hell – PHP is macro hell
every PHP function (or method) has a return value available to you – an automatically NULL zval that you need ot manipulate in order to give information back
it’s called return_value
you manipulate these return value zvals to get data back into PHP userland
the one thing that is
Retval_res used to be retval_resource
Retval string no longer has the duplicate option
When you start to want to return complex data things get a little more complicated – this is where array and object init come in
there are also ways to array_init with a specific length or object_init_ex which allows you to choose the type of object you’re creating
there are a bunch more of these
zend_API.h is your lifeblood for how to use these things, along with
Note that strings used to have the option of saying “duplicate me” or not, now you don’t worry about it, because you’re using a zend_string with refcounts and such
Look at the code and look at the compile
make clean, switch branch,
You have to install uriparser by handls
ls
That means download and build – it has a pretty straightforward system
You can –disable-doc and –disable- I forget (check in code) to ignore bad things
Now we move on to more complex parts of the code, methods that really DO something
remember we should start by writing tests for it
Zend_object can be a variable length now! These can lead to far more complex code if you’re doing evil with objects
We don’t really go over object handlers and other crazy stuff because that’s beyond the scope here of our learning, but something to look up
TO do a class –
create and register it’s CE in minit
put it in another file – will keep yourself sane instead of having 300 mile long files
some people whine that this makes it harder to use static stuff, since each file is compiled into it’s own “unit” and then linked
but modern compilers and linkers make the overhead on this moot – better to be organized!
so this is how you would do your minit function – this would go into php_uriparser.c
where the other code displayed would be in uri.c – where all our code for our uri class is going
it is generally a good idea to keep arginfo and methods to gether as well in the code, so when one changes you remember to change the other
remember stuff must be declared in order to be used too!
the namespace declaration and the PHP_MINIT declaration go into the header file
I often do a private header file for things like that – or do an api file if I allow things in my extension to be used by say other extensions
So this has ONLY the basics – explain how the minit works
then let’s talk lifecycle
Deep breath – let’s talk about those things we put in the module struct
Each are run at a different point in time
let’s also talk a wee bit about structure? sapis?
so this is the lifecycle of PHP
each of these items has a different important role to play
what you need to remember is that minit and mshutdown are called in the opposite order that they are loaded, but you can’t depend on other extensions being around unless you have registered deps (remember way back in the main struct when we talked about deps?
this flow is also true for prefork php webservers
But then we get into threads
When we add threading it gets a little more difficult, because minit/mshutdown are only called when apache is restarted
there’s also ginit and gshutdown but they’re broken
There are multiple declarations to help with this – the ZEND_STRS is a helper macro – again macro hell
So this has ONLY the basics – explain how the minit works
then let’s talk lifecycle
Class constants are another thing that’s pretty easy to do – global constants are evil, do NOT do
then we add some constants for fun
Now let’s make our extension like… actually do something
Methods have several components but look very close to functions that we did earlier. There is a getThis which is available inside that will give you the zval for the class
notice how similar this is to functions!
go over the method stuff just a bit
getTHis is the way you get “this” – notice that no matter how you declare your properties in MINIT, you can “juggle” the vale around depending on what you set it to
go over the method stuff just a bit
Note – traits in extensions are basically broken
these are some more advanced topics
A PHP extension's globals are more properly called the "extension state", since most modules must remember what they're doing between function calls. The "counter" extension is a perfect example of this need: The basic interface calls for a counter with a persistent value. A programmer new to Zend and PHP might do something like this in counter.c to store that value:
This is changed significantly in the way this is stored – as we’re using thread local globals in our thread safe build
efree, emalloc, ecalloc – you can find good documentation on these manual/en/internals2.memory.management.php
zend is taking care of all the memory stuff for you – allocating a larger chunk, cleaning up at the end of the request (but still, efree dammit)
Often, memory needs to be allocated for longer than the duration of a single request. These types of allocations, called persistent allocations because they persist beyond the end of a request, could be performed using the traditional memory allocators because these do not add the additional per-request information used by ZendMM. Sometimes, however, it's not known until runtime whether a particular allocation will need to be persistent or not, so ZendMM exports a set of helper macros that act just like the other memory allocation functions, but have an additional parameter at the end to indicate persistence.
If you genuinely want a persistent allocation, this parameter should be set to one, in which case the request will be passed through to the traditional malloc() family of allocators. If runtime logic has determined that this block does not need to be persistent however, this parameter may be set to zero, and the call will be channeled to the perrequest memory allocator functions.
you’ll do a lot of zend_fetch_object stuff to pick this stuff
Documentation is probably the most important part of the process, but I’ll still leave it for last
If you’ve been writing examples and tests and protos and arginfo all along as I’ve whined about, you’re already 90 percent of the way there with docs, seriously
the easiest way to do this would be to use a generator, however there aren’t any GOOD generators available right now
so just go to svn and copy another extensions stuff – everything is created with PhD so you can test stuff
for pecl you can
put your code anywhere, for phpdoc you need to get your docs roughed out then ask them to be put in svn
also mention readthedocs and the fact that pecl has licensing restrictions and we need a packagist
Go into here about how resources work (an integer pointer to a global table holding resources… or doing some other evil resource storage – basically you’re storing and throwing about pointers and they’re slow (DO NOT)
ini entries are a horrible thing – the use cases are extremely small
threading and such I can rant about for quite a bit
and finally you can override parts of the engine from extensions – this is why xdebug and things like intercept work but they’re a bit beyond the scope of this talk
There is SOOO much more you can do from hooking objects to hooking the engine!
There is SOOO much more you can do from hooking objects to hooking the engine!
