X-Git-Url: https://git.openssl.org/gitweb/?p=openssl.git;a=blobdiff_plain;f=doc%2Fcrypto%2Fthreads.pod;h=37be84fc3973bd364350698527f134fe17d348c8;hp=230cbe890bc3869bdd57886881ab63ee14abe094;hb=8507474564f3f743f5daa3468ca97a9b707b3583;hpb=48fc582f66a58e3da6f095ba1b4498c17581e05a diff --git a/doc/crypto/threads.pod b/doc/crypto/threads.pod index 230cbe890b..37be84fc39 100644 --- a/doc/crypto/threads.pod +++ b/doc/crypto/threads.pod @@ -2,8 +2,9 @@ =head1 NAME -CRYPTO_set_locking_callback, CRYPTO_set_id_callback, -CRYPTO_set_idptr_callback, CRYPTO_num_locks, +CRYPTO_THREADID_set_callback, CRYPTO_THREADID_get_callback, +CRYPTO_THREADID_current, CRYPTO_THREADID_cmp, CRYPTO_THREADID_cpy, +CRYPTO_THREADID_hash, CRYPTO_set_locking_callback, CRYPTO_num_locks, CRYPTO_set_dynlock_create_callback, CRYPTO_set_dynlock_lock_callback, CRYPTO_set_dynlock_destroy_callback, CRYPTO_get_new_dynlockid, CRYPTO_destroy_dynlockid, CRYPTO_lock - OpenSSL thread support @@ -12,21 +13,31 @@ CRYPTO_destroy_dynlockid, CRYPTO_lock - OpenSSL thread support #include - void CRYPTO_set_locking_callback(void (*locking_function)(int mode, - int n, const char *file, int line)); - - void CRYPTO_set_id_callback(unsigned long (*id_function)(void)); - - void CRYPTO_set_idptr_callback(void *(*idptr_function)(void)); + /* Don't use this structure directly. */ + typedef struct crypto_threadid_st + { + void *ptr; + unsigned long val; + } CRYPTO_THREADID; + /* Only use CRYPTO_THREADID_set_[numeric|pointer]() within callbacks */ + void CRYPTO_THREADID_set_numeric(CRYPTO_THREADID *id, unsigned long val); + void CRYPTO_THREADID_set_pointer(CRYPTO_THREADID *id, void *ptr); + int CRYPTO_THREADID_set_callback(void (*threadid_func)(CRYPTO_THREADID *)); + void (*CRYPTO_THREADID_get_callback(void))(CRYPTO_THREADID *); + void CRYPTO_THREADID_current(CRYPTO_THREADID *id); + int CRYPTO_THREADID_cmp(const CRYPTO_THREADID *a, + const CRYPTO_THREADID *b); + void CRYPTO_THREADID_cpy(CRYPTO_THREADID *dest, + const CRYPTO_THREADID *src); + unsigned long CRYPTO_THREADID_hash(const CRYPTO_THREADID *id); int CRYPTO_num_locks(void); - /* struct CRYPTO_dynlock_value needs to be defined by the user */ struct CRYPTO_dynlock_value; void CRYPTO_set_dynlock_create_callback(struct CRYPTO_dynlock_value * - (*dyn_create_function)(char *file, int line)); + (*dyn_create_function)(const char *file, int line)); void CRYPTO_set_dynlock_lock_callback(void (*dyn_lock_function) (int mode, struct CRYPTO_dynlock_value *l, const char *file, int line)); @@ -53,7 +64,8 @@ CRYPTO_destroy_dynlockid, CRYPTO_lock - OpenSSL thread support =head1 DESCRIPTION OpenSSL can safely be used in multi-threaded applications provided -that at least two callback functions are set. +that at least two callback functions are set, locking_function and +threadid_func. locking_function(int mode, int n, const char *file, int line) is needed to perform locking on shared data structures. @@ -68,17 +80,42 @@ B, and releases it otherwise. B and B are the file number of the function setting the lock. They can be useful for debugging. -id_function(void) is a function that returns a numerical thread ID, -for example pthread_self() if it returns an integer (see NOTES below). -By OpenSSL's defaults, this is not needed on Windows nor on platforms -where getpid() returns a different ID for each thread (see NOTES -below). +threadid_func(CRYPTO_THREADID *id) is needed to record the currently-executing +thread's identifier into B. The implementation of this callback should not +fill in B directly, but should use CRYPTO_THREADID_set_numeric() if thread +IDs are numeric, or CRYPTO_THREADID_set_pointer() if they are pointer-based. +If the application does not register such a callback using +CRYPTO_THREADID_set_callback(), then a default implementation is used - on +Windows and BeOS this uses the system's default thread identifying APIs, and on +all other platforms it uses the address of B. The latter is satisfactory +for thread-safety if and only if the platform has a thread-local error number +facility. -idptr_function(void) is a function that similarly returns a thread ID, -but of type void *. This is not needed on platforms where &errno is -different for each thread. OpenSSL assumes that it is in the same -thread iff both the numerical and the pointer thread ID agree, so it -suffices to define one of these two callback functions appropriately. +Once threadid_func() is registered, or if the built-in default implementation is +to be used; + +=over 4 + +=item * +CRYPTO_THREADID_current() records the currently-executing thread ID into the +given B object. + +=item * +CRYPTO_THREADID_cmp() compares two thread IDs (returning zero for equality, ie. +the same semantics as memcmp()). + +=item * +CRYPTO_THREADID_cpy() duplicates a thread ID value, + +=item * +CRYPTO_THREADID_hash() returns a numeric value usable as a hash-table key. This +is usually the exact numeric or pointer-based thread ID used internally, however +this also handles the unusual case where pointers are larger than 'long' +variables and the platform's thread IDs are pointer-based - in this case, mixing +is done to attempt to produce a unique numeric value even though it is not as +wide as the platform's true thread IDs. + +=back Additionally, OpenSSL supports dynamic locks, and sometimes, some parts of OpenSSL need it for better performance. To enable this, the following @@ -150,24 +187,6 @@ You can find out if OpenSSL was configured with thread support: Also, dynamic locks are currently not used internally by OpenSSL, but may do so in the future. -Defining id_function(void) has it's own issues. Generally speaking, -pthread_self() should be used, even on platforms where getpid() gives -different answers in each thread, since that may depend on the machine -the program is run on, not the machine where the program is being -compiled. For instance, Red Hat 8 Linux and earlier used -LinuxThreads, whose getpid() returns a different value for each -thread. Red Hat 9 Linux and later use NPTL, which is -Posix-conformant, and has a getpid() that returns the same value for -all threads in a process. A program compiled on Red Hat 8 and run on -Red Hat 9 will therefore see getpid() returning the same value for -all threads. - -There is still the issue of platforms where pthread_self() returns -something other than an integer. It is for cases like this that -CRYPTO_set_idptr_callback() comes in handy. (E.g., call malloc(1) -once in each thread, and have idptr_function() return a pointer to -this object.) - =head1 EXAMPLES B shows examples of the callback functions on @@ -175,12 +194,14 @@ Solaris, Irix and Win32. =head1 HISTORY -CRYPTO_set_locking_callback() and CRYPTO_set_id_callback() are +CRYPTO_set_locking_callback() is available in all versions of SSLeay and OpenSSL. CRYPTO_num_locks() was added in OpenSSL 0.9.4. All functions dealing with dynamic locks were added in OpenSSL 0.9.5b-dev. - -CRYPTO_set_idptr_callback() was added in OpenSSL 0.9.9. +B and associated functions were introduced in OpenSSL 1.0.0 +to replace (actually, deprecate) the previous CRYPTO_set_id_callback(), +CRYPTO_get_id_callback(), and CRYPTO_thread_id() functions which assumed +thread IDs to always be represented by 'unsigned long'. =head1 SEE ALSO