diff options
Diffstat (limited to 'erts/doc/src/erlang.xml')
| -rw-r--r-- | erts/doc/src/erlang.xml | 74 |
1 files changed, 69 insertions, 5 deletions
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml index cd9bb85f5c..c8fe7b4bd2 100644 --- a/erts/doc/src/erlang.xml +++ b/erts/doc/src/erlang.xml @@ -253,6 +253,54 @@ iolist() = [char() | binary() | iolist()] </desc> </func> <func> + <name>binary_part(Subject, PosLen) -> binary()</name> + <fsummary>Extracts a part of a binary</fsummary> + <type> + <v>Subject = binary()</v> + <v>PosLen = {Start,Length}</v> + <v>Start = int()</v> + <v>Length = int()</v> + </type> + <desc> + <p>Extracts the part of the binary described by <c>PosLen</c>.</p> + + <p>Negative length can be used to extract bytes at the end of a binary:</p> + +<code> +1> Bin = <<1,2,3,4,5,6,7,8,9,10>>. +2> binary_part(Bin,{byte_size(Bin), -5)). +<<6,7,8,9,10>> +</code> + + <p>If <c>PosLen</c> in any way references outside the binary, a <c>badarg</c> exception is raised.</p> + + <p><c>Start</c> is zero-based, i.e:</p> +<code> +1> Bin = <<1,2,3>> +2> binary_part(Bin,{0,2}). +<<1,2>> +</code> + + <p>See the STDLIB module <c>binary</c> for details about the <c>PosLen</c> semantics.</p> + + <p>Allowed in guard tests.</p> + </desc> + </func> + <func> + <name>binary_part(Subject, Start, Length) -> binary()</name> + <fsummary>Extracts a part of a binary</fsummary> + <type> + <v>Subject = binary()</v> + <v>Start = int()</v> + <v>Length = int()</v> + </type> + <desc> + <p>The same as <c>binary_part(Subject, {Pos, Len})</c>.</p> + + <p>Allowed in guard tests.</p> + </desc> + </func> + <func> <name>binary_to_atom(Binary, Encoding) -> atom()</name> <fsummary>Convert from text representation to an atom</fsummary> <type> @@ -318,6 +366,11 @@ iolist() = [char() | binary() | iolist()] corresponding to the bytes from position <c>Start</c> to position <c>Stop</c> in <c>Binary</c>. Positions in the binary are numbered starting from 1.</p> + + <note><p>This function's indexing style of using one-based indices for + binaries is deprecated. New code should use the functions in + the STDLIB module <c>binary</c> instead. They consequently + use the same (zero-based) style of indexing.</p></note> </desc> </func> <func> @@ -354,7 +407,7 @@ iolist() = [char() | binary() | iolist()] </desc> </func> <func> - <name>erlang:binary_to_term(Binary, Opts) -> term()</name> + <name>binary_to_term(Binary, Opts) -> term()</name> <fsummary>Decode an Erlang external term format binary</fsummary> <type> <v>Opts = [safe]</v> @@ -5103,10 +5156,21 @@ true</pre> For more information on how to define the CPU topology, see <seealso marker="#system_flag_cpu_topology">erlang:system_flag(cpu_topology, CpuTopology)</seealso>. </p> - <p><em>NOTE:</em> If other programs on the system have bound - to processors, e.g. another Erlang runtime system, you - may lose performance when binding schedulers. Therefore, - schedulers are by default not bound.</p> + <p>The runtime system will by default bind schedulers to logical + processors using the <c>default_bind</c> bind type if the amount + of schedulers are at least equal to the amount of logical + processors configured, binding of schedulers is supported, + and a CPU topology is available at startup. + </p> + <p><em>NOTE:</em> If the Erlang runtime system is the only + operating system process that binds threads to logical processors, + this improves the performance of the runtime system. However, + if other operating system processes (as for example another Erlang + runtime system) also bind threads to logical processors, there + might be a performance penalty instead. If this is the case you, + are are advised to unbind the schedulers using the + <seealso marker="erl#+sbt">+sbtu</seealso> command line argument, + or <c>erlang:system_flag(scheduler_bind_type, unbound)</c>.</p> <p>Schedulers can be bound in different ways. The <c>How</c> argument determines how schedulers are bound. <c>How</c> can currently be one of:</p> |