diff --git a/ChangeLog b/ChangeLog index 0ae7f74f6..f68af52c7 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,7 @@ +2015-01-14 Werner Lemberg + + * docs/CHANGES: Updated, using a description from Behdad. + 2015-01-14 Behdad Esfahbod * src/autofit/afmodule.c (af_autofitter_done): Fix compiler warning. diff --git a/docs/CHANGES b/docs/CHANGES index bbc31104a..1d2d33933 100644 --- a/docs/CHANGES +++ b/docs/CHANGES @@ -1,4 +1,29 @@ +CHANGES BETWEEN 2.5.5 and 2.5.6 + + II. IMPORTANT CHANGES + + - Behdad Esfahbod contributed code for improved thread-safety, + which results in the following model. + + * An `FT_Face' object can only be safely used from one thread at + a time. + + * An `FT_Library' object can now be used without modification + from multiple threads at the same time. + + * `FT_Face' creation and destruction with the same `FT_Library' + object can only be done from one thread at a time. + + One can use a single `FT_Library' object across threads as long + as a mutex lock is used around `FT_New_Face' and `FT_Done_Face'. + Any calls to `FT_Load_Glyph' and similar API are safe and do not + need the lock to be held as long as the same `FT_Face' is not + used from multiple threads at the same time. + + +====================================================================== + CHANGES BETWEEN 2.5.4 and 2.5.5 I. IMPORTANT BUG FIXES diff --git a/include/freetype.h b/include/freetype.h index 27fd44bfc..10227194c 100644 --- a/include/freetype.h +++ b/include/freetype.h @@ -394,8 +394,11 @@ FT_BEGIN_HEADER /* It also embeds a memory manager (see @FT_Memory), as well as a */ /* scan-line converter object (see @FT_Raster). */ /* */ - /* In multi-threaded applications, make sure that the same FT_Library */ - /* object or any of its children doesn't get accessed in parallel. */ + /* In multi-threaded applications it is easiest to use one */ + /* `FT_Library' object per thread. In case this is too cumbersome, */ + /* a single `FT_Library' object across threads is possible also */ + /* (since FreeType version 2.5.6), as long as a mutex lock is used */ + /* around @FT_New_Face and @FT_Done_Face. */ /* */ /* */ /* Library objects are normally created by @FT_Init_FreeType, and */ @@ -477,6 +480,14 @@ FT_BEGIN_HEADER /* */ /* Use @FT_Done_Face to destroy it (along with its slot and sizes). */ /* */ + /* An `FT_Face' object can only be safely used from one thread at a */ + /* time. Similarly, creation and destruction of `FT_Face' with the */ + /* same @FT_Library object can only be done from one thread at a */ + /* time. On the other hand, functions like @FT_Load_Glyph and its */ + /* siblings are thread-safe and do not need the lock to be held as */ + /* long as the same `FT_Face' object is not used from multiple */ + /* threads at the same time. */ + /* */ /* */ /* See @FT_FaceRec for the publicly accessible fields of a given face */ /* object. */ @@ -1769,8 +1780,8 @@ FT_BEGIN_HEADER /* use @FT_New_Library instead, followed by a call to */ /* @FT_Add_Default_Modules (or a series of calls to @FT_Add_Module). */ /* */ - /* For multi-threading applications each thread should have its own */ - /* FT_Library object. */ + /* See the documentation of @FT_Library and @FT_Face for */ + /* multi-threading issues. */ /* */ /* If you need reference-counting (cf. @FT_Reference_Library), use */ /* @FT_New_Library and @FT_Done_Library. */