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@@ -30,6 +30,419 @@
</header>
<p>This document describes the changes made to the STDLIB application.</p>
+<section><title>STDLIB 1.17.1</title>
+
+ <section><title>Fixed Bugs and Malfunctions</title>
+ <list>
+ <item>
+ <p>reference() has been substituted for ref() in the
+ documentation.</p>
+ <p>
+ Own Id: OTP-8733</p>
+ </item>
+ </list>
+ </section>
+
+
+ <section><title>Improvements and New Features</title>
+ <list>
+ <item>
+ <p>
+ The ms_transform now warns if the fun head shadows
+ surrounding variables (just like the warnings you would
+ get for an ordinary fun in the same context).</p>
+ <p>
+ Own Id: OTP-6759</p>
+ </item>
+ <item>
+ <p>
+ ets:select_reverse/{1,2,3} are now documented.</p>
+ <p>
+ Own Id: OTP-7863</p>
+ </item>
+ <item>
+ <p>
+ Large parts of the <c>ethread</c> library have been
+ rewritten. The <c>ethread</c> library is an Erlang
+ runtime system internal, portable thread library used by
+ the runtime system itself.</p>
+ <p>
+ Most notable improvement is a reader optimized rwlock
+ implementation which dramatically improve the performance
+ of read-lock/read-unlock operations on multi processor
+ systems by avoiding ping-ponging of the rwlock cache
+ lines. The reader optimized rwlock implementation is used
+ by miscellaneous rwlocks in the runtime system that are
+ known to be read-locked frequently, and can be enabled on
+ ETS tables by passing the <seealso
+ marker="stdlib:ets#new_2_read_concurrency">{read_concurrency,
+ true}</seealso> option upon table creation. See the
+ documentation of <seealso
+ marker="stdlib:ets#new/2">ets:new/2</seealso> for more
+ information. The reader optimized rwlock implementation
+ can be fine tuned when starting the runtime system. For
+ more information, see the documentation of the <seealso
+ marker="erts:erl#+rg">+rg</seealso> command line argument
+ of <c>erl</c>.</p>
+ <p>
+ There is also a new implementation of rwlocks that is not
+ optimized for readers. Both implementations interleaves
+ readers and writers during contention as opposed to,
+ e.g., the NPTL (Linux) pthread rwlock implementation
+ which use either a reader or writer preferred strategy.
+ The reader/writer preferred strategy is problematic since
+ it starves threads doing the non-preferred operation.</p>
+ <p>
+ The new rwlock implementations in general performs better
+ in ERTS than common pthread implementations. However, in
+ some extremely heavily contended cases this is not the
+ case. Such heavy contention can more or less only appear
+ on ETS tables. This when multiple processes do very large
+ amounts of write locked operations simultaneously on the
+ same table. Such use of ETS is bad regardless of rwlock
+ implementation, will never scale, and is something we
+ strongly advise against.</p>
+ <p>
+ The new rwlock implementations depend on atomic
+ operations. If no native atomic implementation is found,
+ a fallback solution will be used. Using the fallback
+ implies a performance degradation. That is, it is more
+ important now than before to build OTP with a native
+ atomic implementation.</p>
+ <p>
+ The <c>ethread</c> library contains native atomic
+ implementations for, x86 (32 and 64 bit), powerpc (32
+ bit), sparc V9 (32 and 64 bit), and tilera (32 bit). On
+ other hardware gcc's builtin support for atomic memory
+ access will be used if such exists. If no such support is
+ found, <c>configure</c> will warn about no atomic
+ implementation available.</p>
+ <p>
+ The <c>ethread</c> library can now also use the
+ <c>libatomic_ops</c> library for atomic memory accesses.
+ This makes it possible for the Erlang runtime system to
+ utilize optimized native atomic operations on more
+ platforms than before. If <c>configure</c> warns about no
+ atomic implementation available, try using the
+ <c>libatomic_ops</c> library. Use the <seealso
+ marker="doc/installation_guide:INSTALL#How-to-Build-and-Install-ErlangOTP_A-Closer-Look-at-the-individual-Steps_Configuring">--with-libatomic_ops=PATH</seealso>
+ <c>configure</c> command line argument when specifying
+ where the <c>libatomic_ops</c> installation is located.
+ The <c>libatomic_ops</c> library can be downloaded from:
+ <url
+ href="http://www.hpl.hp.com/research/linux/atomic_ops/">http://www.hpl.hp.com/research/linux/atomic_ops/</url></p>
+ <p>
+ The changed API of the <c>ethread</c> library has also
+ caused modifications in the Erlang runtime system.
+ Preparations for the to come "delayed deallocation"
+ feature has also been done since it depends on the
+ <c>ethread</c> library.</p>
+ <p>
+ <em>Note</em>: When building for x86, the <c>ethread</c>
+ library will now use instructions that first appeared on
+ the pentium 4 processor. If you want the runtime system
+ to be compatible with older processors (back to 486) you
+ need to pass the <seealso
+ marker="doc/installation_guide:INSTALL#How-to-Build-and-Install-ErlangOTP_A-Closer-Look-at-the-individual-Steps_Configuring">--enable-ethread-pre-pentium4-compatibility</seealso>
+ <c>configure</c> command line argument when configuring
+ the system.</p>
+ <p>
+ Own Id: OTP-8544</p>
+ </item>
+ <item>
+ <p>
+ Some Built In Functions (BIFs) from the module erlang was
+ never made autoimported for backward compatibility
+ reasons. As local functions now override autoimports, new
+ autoimports is no longer a problem, why the following
+ BIFs are finally made autoimported: monitor/2, monitor/3,
+ demonitor/2, demonitor/3, error/1, error/2,
+ integer_to_list/2, list_to_integer/2.</p>
+ <p>
+ Own Id: OTP-8763</p>
+ </item>
+ </list>
+ </section>
+
+</section>
+
+<section><title>STDLIB 1.17</title>
+
+ <section><title>Fixed Bugs and Malfunctions</title>
+ <list>
+ <item>
+ <p>The Erlang code preprocessor (<c>epp</c>) sent extra
+ messages on the form <c>{eof,Location}</c> to the client
+ when parsing the <c>file</c> attribute. This bug,
+ introduced in R11B, has been fixed.</p>
+ <p>
+ Own Id: OTP-8470</p>
+ </item>
+ <item>
+ <p>The abstract type 'fun' could not be printed by the
+ Erlang pretty printer (<c>erl_pp</c>). This bug has been
+ fixed.</p>
+ <p>
+ Own Id: OTP-8473</p>
+ </item>
+ <item>
+ <p>The function <c>erl_scan:reserved_word/1</c> no longer
+ returns <c>true</c> when given the word <c>spec</c>. This
+ bug was introduced in STDLIB-1.15.3 (R12B-3).</p>
+ <p>
+ Own Id: OTP-8567</p>
+ </item>
+ <item>
+ <p>The documentation of <c>lists:keysort/2</c> states
+ that the sort is stable.</p>
+ <p>
+ Own Id: OTP-8628 Aux Id: seq11576 </p>
+ </item>
+ <item>
+ <p>
+ The shell's line editing has been improved to more
+ resemble the behaviour of readline and other shells.
+ (Thanks to Dave Peticolas)</p>
+ <p>
+ Own Id: OTP-8635</p>
+ </item>
+ <item>
+ <p>The Erlang code preprocessor (<c>epp</c>) did not
+ correctly handle premature end-of-input when defining
+ macros. This bug, introduced in STDLIB 1.16, has been
+ fixed.</p>
+ <p>
+ Own Id: OTP-8665 Aux Id: OTP-7810 </p>
+ </item>
+ </list>
+ </section>
+
+
+ <section><title>Improvements and New Features</title>
+ <list>
+ <item>
+ <p>
+ The module binary from EEP31 (and EEP9) is implemented.</p>
+ <p>
+ Own Id: OTP-8217</p>
+ </item>
+ <item>
+ <p>The erlang pretty printer (<c>erl_pp</c>) no longer
+ quotes atoms in types.</p>
+ <p>
+ Own Id: OTP-8501</p>
+ </item>
+ <item>
+ <p>The Erlang code preprocessor (<c>epp</c>) now
+ considers records with no fields as typed.</p>
+ <p>
+ Own Id: OTP-8503</p>
+ </item>
+ <item>
+ <p>
+ Added function <c>zip:foldl/3</c> to iterate over zip
+ archives.</p>
+ <p>
+ Added functions to create and extract escripts. See
+ <c>escript:create/2</c> and <c>escript:extract/2</c>.</p>
+ <p>
+ The undocumented function <c>escript:foldl/3</c> has been
+ removed. The same functionality can be achieved with the
+ more flexible functions <c>escript:extract/2</c> and
+ <c>zip:foldl/3</c>.</p>
+ <p>
+ Record fields has been annotated with type info. Source
+ files as been adapted to fit within 80 chars and trailing
+ whitespace has been removed.</p>
+ <p>
+ Own Id: OTP-8521</p>
+ </item>
+ <item>
+ <p>The Erlang parser no longer duplicates the singleton
+ type <c>undefined</c> in the type of record fields
+ without initial value.</p>
+ <p>
+ Own Id: OTP-8522</p>
+ </item>
+ <item>
+ <p>A regular expression with many levels of parenthesis
+ could cause a buffer overflow. That has been corrected.
+ (Thanks to Michael Santos.)</p>
+ <p>
+ Own Id: OTP-8539</p>
+ </item>
+ <item>
+ <p>When defining macros the closing right parenthesis
+ before the dot is now mandatory.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-8562</p>
+ </item>
+ <item>
+ <p>
+ Some properties of a compiled re pattern are defined to
+ allow for guard tests.</p>
+ <p>
+ Own Id: OTP-8577</p>
+ </item>
+ <item>
+ <p>Local and imported functions now override the
+ auto-imported BIFs when the names clash. The pre R14
+ behaviour was that auto-imported BIFs would override
+ local functions. To avoid that old programs change
+ behaviour, the following will generate an error:</p>
+ <list><item><p>Doing a call without explicit module name
+ to a local function having a name clashing with the name
+ of an auto-imported BIF that was present (and
+ auto-imported) before OTP R14A</p></item>
+ <item><p>Explicitly importing a function having a name
+ clashing with the name of an autoimported BIF that was
+ present (and autoimported) before OTP R14A</p></item>
+ <item><p>Using any form of the old compiler directive
+ <c>nowarn_bif_clash</c></p></item> </list> <p>If the BIF
+ was added or auto-imported in OTP R14A or later,
+ overriding it with an import or a local function will
+ only result in a warning,</p> <p>To resolve clashes, you
+ can either use the explicit module name <c>erlang</c> to
+ call the BIF, or you can remove the auto-import of that
+ specific BIF by using the new compiler directive
+ <c>-compile({no_auto_import,[F/A]}).</c>, which makes all
+ calls to the local or imported function without explicit
+ module name pass without warnings or errors.</p> <p>The
+ change makes it possible to add auto-imported BIFs
+ without breaking or silently changing old code in the
+ future. However some current code ingeniously utilizing
+ the old behaviour or the <c>nowarn_bif_clash</c> compiler
+ directive, might need changing to be accepted by the
+ compiler.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-8579</p>
+ </item>
+ <item>
+ <p>The undocumented, unsupport, and deprecated function
+ <c>lists:flat_length/1</c> has been removed.</p>
+ <p>
+ Own Id: OTP-8584</p>
+ </item>
+ <item>
+ <p>
+ A bug in re that could cause certain regular expression
+ matches never to terminate is corrected. (Thanks to
+ Michael Santos and Gordon Guthrie.)</p>
+ <p>
+ Own Id: OTP-8589</p>
+ </item>
+ <item>
+ <p>Nested records can now be accessed without
+ parenthesis. See the Reference Manual for examples.
+ (Thanks to YAMASHINA Hio and Tuncer Ayaz.)</p>
+ <p>
+ Own Id: OTP-8597</p>
+ </item>
+ <item>
+ <p><c>receive</c> statements that can only read out a
+ newly created reference are now specially optimized so
+ that it will execute in constant time regardless of the
+ number of messages in the receive queue for the process.
+ That optimization will benefit calls to
+ <c>gen_server:call()</c>. (See <c>gen:do_call/4</c> for
+ an example of a receive statement that will be
+ optimized.)</p>
+ <p>
+ Own Id: OTP-8623</p>
+ </item>
+ <item>
+ <p>The beam_lib:cmp/2 function now compares BEAM files in
+ stricter way. The BEAM files will be considered different
+ if there are any changes except in the compilation
+ information ("CInf") chunk. beam_lib:cmp/2 used to ignore
+ differences in the debug information (significant for
+ Dialyzer) and other chunks that did not directly change
+ the run-time behavior.</p>
+ <p>
+ Own Id: OTP-8625</p>
+ </item>
+ <item>
+ <p>
+ When a gen_server, gen_fsm process, or gen_event
+ terminates abnormally, sometimes the text representation
+ of the process state can occupy many lines of the error
+ log, depending on the definition of the state term. A
+ mechanism to trim out parts of the state from the log has
+ been added (using a format_status/2 callback). See the
+ documentation.</p>
+ <p>
+ Own Id: OTP-8630</p>
+ </item>
+ <item>
+ <p>
+ Calling <c>sys:get_status()</c> for processes that have
+ globally registered names that were not atoms would cause
+ a crash. Corrected. (Thanks to Steve Vinoski.)</p>
+ <p>
+ Own Id: OTP-8656</p>
+ </item>
+ <item>
+ <p>The Erlang scanner has been augmented with two new
+ tokens: <c>..</c> and <c>...</c>.</p>
+ <p>
+ Own Id: OTP-8657</p>
+ </item>
+ <item>
+ <p>Expressions evaluating to integers can now be used in
+ types and function specifications where hitherto only
+ integers were allowed ("Erlang_Integer").</p>
+ <p>
+ Own Id: OTP-8664</p>
+ </item>
+ <item>
+ <p>The compiler optimizes record operations better.</p>
+ <p>
+ Own Id: OTP-8668</p>
+ </item>
+ <item>
+ <p>
+ The recently added BIFs erlang:min/2, erlang:max/2 and
+ erlang:port_command/3 are now auto-imported (as they were
+ originally intended to be). Due to the recent compiler
+ change (OTP-8579), the only impact on old code defining
+ it's own min/2, max/2 or port_command/3 functions will be
+ a warning, the local functions will still be used. The
+ warning can be removed by using
+ -compile({no_auto_import,[min/2,max/2,port_command/3]}).
+ in the source file.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-8669 Aux Id: OTP-8579 </p>
+ </item>
+ <item>
+ <p>
+ Now, binary_to_term/2 is auto-imported. This will cause a
+ compile warning if and only if a module has got a local
+ function with that name.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-8671</p>
+ </item>
+ <item>
+ <p>
+ The predefined builtin type tid() has been removed.
+ Instead, ets:tid() should be used.</p>
+ <p>
+ *** POTENTIAL INCOMPATIBILITY ***</p>
+ <p>
+ Own Id: OTP-8687</p>
+ </item>
+ </list>
+ </section>
+
+</section>
+
<section><title>STDLIB 1.16.5</title>
<section><title>Fixed Bugs and Malfunctions</title>
@@ -50,7 +463,7 @@
<item>
<p>A number of bugs concerning re and unicode are
corrected:</p>
- <p>re:compile no longer looses unicode option, which also
+ <p>re:compile no longer loses unicode option, which also
fixes bug in re:split.</p>
<p>re:replace now handles unicode charlist replacement
argument</p>