diff options
Diffstat (limited to 'openssl/doc/crypto/threads.pod')
| -rw-r--r-- | openssl/doc/crypto/threads.pod | 91 |
1 files changed, 63 insertions, 28 deletions
diff --git a/openssl/doc/crypto/threads.pod b/openssl/doc/crypto/threads.pod index 3df4ecd77..dc0e9391d 100644 --- a/openssl/doc/crypto/threads.pod +++ b/openssl/doc/crypto/threads.pod @@ -2,7 +2,9 @@ =head1 NAME -CRYPTO_set_locking_callback, CRYPTO_set_id_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 @@ -11,14 +13,26 @@ CRYPTO_destroy_dynlockid, CRYPTO_lock - OpenSSL thread support #include <openssl/crypto.h> - 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; @@ -50,7 +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. @@ -65,10 +80,42 @@ B<CRYPTO_LOCK>, and releases it otherwise. B<file> and B<line> 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, for example -pthread_self() if it returns an integer (see NOTES below). It isn't -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<id>. The implementation of this callback should not +fill in B<id> 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<errno>. 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<id> 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 @@ -140,22 +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. This is a bit unusual, and this -manual has no cookbook solution for that case. - =head1 EXAMPLES B<crypto/threads/mttest.c> shows examples of the callback functions on @@ -163,10 +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<CRYPTO_THREADID> 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 |