Provide documentation for all SSL(_CTX)?_(get|set)(_default)?_read_ahead

[openssl.git] / doc / crypto / threads.pod

diff --git a/doc/crypto/threads.pod b/doc/crypto/threads.pod
index bcaa94d1bb8a8b135a7d271e63b4262a295f80bd..37be84fc3973bd364350698527f134fe17d348c8 100644 (file)
--- a/doc/crypto/threads.pod
+++ b/doc/crypto/threads.pod
@@ -2,7 +2,9 @@
 
 =head1 NAME
 
 
 =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
 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


@@ -11,19 +13,31 @@ CRYPTO_destroy_dynlockid, CRYPTO_lock - OpenSSL thread support
 
  #include <openssl/crypto.h>
 
 
  #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);
 
 
  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 *
  /* 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));
  void CRYPTO_set_dynlock_lock_callback(void (*dyn_lock_function)
        (int mode, struct CRYPTO_dynlock_value *l,
        const char *file, int line));


@@ -50,11 +64,14 @@ CRYPTO_destroy_dynlockid, CRYPTO_lock - OpenSSL thread support
 =head1 DESCRIPTION
 
 OpenSSL can safely be used in multi-threaded applications provided
 =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
 
 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<n>-th lock if B<mode> &
 
 locking_function() must be able to handle up to CRYPTO_num_locks()
 different mutex locks. It sets the B<n>-th lock if B<mode> &


@@ -63,9 +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.
 
 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. 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<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
 
 Additionally, OpenSSL supports dynamic locks, and sometimes, some parts
 of OpenSSL need it for better performance.  To enable this, the following


@@ -89,7 +139,7 @@ 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)
 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 nunmbered n. Multi-threaded
+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
 applications might crash at random if it is not set.
 
 dyn_destroy_function(CRYPTO_dynlock *l, const char *file, int line) is


@@ -106,7 +156,7 @@ 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
 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 behavior if misused (for example, CRYPTO_READ and CRYPTO_WRITE
+undefined behaviour if misused (for example, CRYPTO_READ and CRYPTO_WRITE

 should not be used together):
 
        CRYPTO_LOCK     0x01
 should not be used together):
 
        CRYPTO_LOCK     0x01


@@ -122,13 +172,13 @@ CRYPTO_get_new_dynlockid() returns the index to the newly created lock.
 
 The other functions return no values.
 
 
 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 <openssl/opensslconf.h>
 
 You can find out if OpenSSL was configured with thread support:
 
  #define OPENSSL_THREAD_DEFINES
  #include <openssl/opensslconf.h>

- #if defined(THREADS)
+ #if defined(OPENSSL_THREADS)

    // thread support enabled
  #else
    // no thread support
    // thread support enabled
  #else
    // no thread support


@@ -144,10 +194,14 @@ Solaris, Irix and Win32.
 
 =head1 HISTORY
 
 
 =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.
 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
 
 
 =head1 SEE ALSO