X-Git-Url: https://git.openssl.org/?p=openssl.git;a=blobdiff_plain;f=doc%2Fcrypto%2Fthreads.pod;h=a1e44311219a7bc93811aa703975ab68c3d5635d;hp=5da056f3f82366182888269b41727088441c24fb;hb=ab9c689ad387fcd209017fe45985b1938a0ee0df;hpb=e0b8b39f3a4cfbaf6e79a7db379e6d5af589835d diff --git a/doc/crypto/threads.pod b/doc/crypto/threads.pod index 5da056f3f8..a1e4431121 100644 --- a/doc/crypto/threads.pod +++ b/doc/crypto/threads.pod @@ -2,27 +2,76 @@ =head1 NAME -CRYPTO_set_locking_callback, CRYPTO_set_id_callback - OpenSSL thread support +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 =head1 SYNOPSIS #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)); + /* 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)); + void CRYPTO_set_dynlock_lock_callback(void (*dyn_lock_function) + (int mode, struct CRYPTO_dynlock_value *l, + const char *file, int line)); + void CRYPTO_set_dynlock_destroy_callback(void (*dyn_destroy_function) + (struct CRYPTO_dynlock_value *l, const char *file, int line)); + + int CRYPTO_get_new_dynlockid(void); + + void CRYPTO_destroy_dynlockid(int i); + + void CRYPTO_lock(int mode, int n, const char *file, int line); + + #define CRYPTO_w_lock(type) \ + CRYPTO_lock(CRYPTO_LOCK|CRYPTO_WRITE,type,__FILE__,__LINE__) + #define CRYPTO_w_unlock(type) \ + CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_WRITE,type,__FILE__,__LINE__) + #define CRYPTO_r_lock(type) \ + CRYPTO_lock(CRYPTO_LOCK|CRYPTO_READ,type,__FILE__,__LINE__) + #define CRYPTO_r_unlock(type) \ + CRYPTO_lock(CRYPTO_UNLOCK|CRYPTO_READ,type,__FILE__,__LINE__) + #define CRYPTO_add(addr,amount,type) \ + CRYPTO_add_lock(addr,amount,type,__FILE__,__LINE__) + =head1 DESCRIPTION OpenSSL can safely be used in multi-threaded applications provided -that 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 stuctures. Multi-threaded -applications will crash at random if it is not set. +needed to perform locking on shared data structures. +(Note that OpenSSL uses a number of global data structures that +will be implicitly shared whenever multiple threads use OpenSSL.) +Multi-threaded applications will crash at random if it is not set. locking_function() must be able to handle up to CRYPTO_num_locks() different mutex locks. It sets the B-th lock if B & @@ -31,27 +80,113 @@ 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 thread ID. It is not -needed on Windows nor on platforms where getpid() returns a different -ID for each thread (most notably Linux). +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. + +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 +is required: + +=over 4 + +=item * +Three additional callback function, dyn_create_function, dyn_lock_function +and dyn_destroy_function. + +=item * +A structure defined with the data that each lock needs to handle. + +=back + +struct CRYPTO_dynlock_value has to be defined to contain whatever structure +is needed to handle locks. + +dyn_create_function(const char *file, int line) is needed to create a +lock. Multi-threaded applications might crash at random if it is not set. + +dyn_lock_function(int mode, CRYPTO_dynlock *l, const char *file, int line) +is needed to perform locking off dynamic lock numbered n. Multi-threaded +applications might crash at random if it is not set. + +dyn_destroy_function(CRYPTO_dynlock *l, const char *file, int line) is +needed to destroy the lock l. Multi-threaded applications might crash at +random if it is not set. + +CRYPTO_get_new_dynlockid() is used to create locks. It will call +dyn_create_function for the actual creation. + +CRYPTO_destroy_dynlockid() is used to destroy locks. It will call +dyn_destroy_function for the actual destruction. + +CRYPTO_lock() is used to lock and unlock the locks. mode is a bitfield +describing what should be done with the lock. n is the number of the +lock as returned from CRYPTO_get_new_dynlockid(). mode can be combined +from the following values. These values are pairwise exclusive, with +undefined behaviour if misused (for example, CRYPTO_READ and CRYPTO_WRITE +should not be used together): + + CRYPTO_LOCK 0x01 + CRYPTO_UNLOCK 0x02 + CRYPTO_READ 0x04 + CRYPTO_WRITE 0x08 =head1 RETURN VALUES CRYPTO_num_locks() returns the required number of locks. + +CRYPTO_get_new_dynlockid() returns the index to the newly created lock. + The other functions return no values. -=head1 NOTE +=head1 NOTES You can find out if OpenSSL was configured with thread support: #define OPENSSL_THREAD_DEFINES #include - #if defined(THREADS) + #if defined(OPENSSL_THREADS) // thread support enabled #else // no thread support #endif +Also, dynamic locks are currently not used internally by OpenSSL, but +may do so in the future. + =head1 EXAMPLES B shows examples of the callback functions on @@ -59,9 +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. +B and associated functions were introduced in OpenSSL 0.9.9 +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