Ruby » Ruby master

merge revision(s) 57469,57471,57472,57503,57508: [Backport #13299]

    io.c: recycle garbage on write

    * string.c (STR_IS_SHARED_M): new flag to mark shared mulitple times
      (STR_SET_SHARED): set STR_IS_SHARED_M
      (rb_str_tmp_frozen_acquire, rb_str_tmp_frozen_release): new functions
      (str_new_frozen): set/unset STR_IS_SHARED_M as appropriate
    * internal.h: declare new functions
    * io.c (fwrite_arg, fwrite_do, fwrite_end): new
      (io_fwrite): use new functions

    Introduce rb_str_tmp_frozen_acquire and rb_str_tmp_frozen_release
    to manage a hidden, frozen string.  Reuse one bit of the embed
    length for shared strings as STR_IS_SHARED_M to indicate a string
    has been shared multiple times.  In the common case, the string
    is only shared once so the object slot can be reclaimed immediately.

    minimum results in each 3 measurements. (time and size)

    Execution time (sec)
    name                            trunk   built
    io_copy_stream_write            0.682   0.254
    io_copy_stream_write_socket     1.225   0.751

    Speedup ratio: compare with the result of `trunk' (greater is better)
    name    built
    io_copy_stream_write            2.680
    io_copy_stream_write_socket     1.630

    Memory usage (last size) (B)
    name                            trunk           built
    io_copy_stream_write            95436800.000    6512640.000
    io_copy_stream_write_socket     117628928.000   7127040.000

    Memory consuming ratio (size) with the result of `trunk' (greater is better)
    name    built
    io_copy_stream_write            14.654
    io_copy_stream_write_socket     16.505
    string.c (rb_str_tmp_frozen_release): release embedded strings

    Handle the embedded case first, since we may have an embedded
    duplicate and non-embedded original string.

    * string.c (rb_str_tmp_frozen_release): handled embedded strings
    * test/ruby/test_io.rb (test_write_no_garbage): new test
      [ruby-core:78898] [Bug #13085]
    io.c (rb_io_syswrite): avoid leaving garbage after write

    As with IO#write, IO#syswrite also generates garbage which can
    be harmful in hand-coded read-write loops.

    * io.c (swrite_arg, swrite_do, swrite_end): new
      (rb_io_syswrite): use new functions to cleanup garbage
      [ruby-core:78898] [Bug #13085]
    Add class name to assert messages
    io.c: remove rb_ensure usage for rb_str_tmp_frozen_* calls

    Using rb_ensure pessimizes the common case and makes the code
    more difficult to read and follow.  If we hit an exceptions
    during write, just let the GC handle cleanup as the exception
    is already bad for garbage.

    * io.c (io_fwrite): call rb_str_tmp_frozen{acquire,release} directly
      (rb_io_syswrite): ditto
      (fwrite_do, fwrite_end, swrite_do, swrite_end): remove

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_4@57941 b2dd03c8-39d4-4d8f-98ff-823fe69b080e