Commits on Feb 10, 2015

1. Refactor to reduce dependancy on ios.c …

   Rationale:
   
       Unravel ios.c’s legacy role as debug io library for the runtime;
       vs current role as backend for iostream.jl.
   
   Clean up historical debug printf functions:
   
       Replace calls to ios_printf(), ios_puts(), JL_PRINTF, JL_PUTS etc
       with jl_printf(), jl_puts()...
   
       Replace exit() with jl_exit() in repl.c, dump.c and init.c.
   
   Make jl_printf() and jl_exit() safe in early initialisation.
   
   Remove ios.c dependance from ast.c and builtins.c:
   
       src/flisp/flisp.c:
   
           New fl_load_system_image_str(char*, size_t)
           Hides detail of ios_static_buffer from ast.c
           ios_* no longer used in ast.c.
   
       src/builtins.c
   
           In jl_errorf(), replace ios_vprintf() with vasprintf()
           (following the precedent set by src/jl_uv.c:663).
   
   Use free() not LLT_FREE() to clean up after vasprintf() in jl_uv.c:
   
       man vasprintf says “asprintf() and vasprintf() dynamically
                           allocate a new string with malloc(3)”
   
   Refactor pairs of calls to jl_printf() & jl_exit(1) into calls to
   jl_error[f](), which does the same thing during early init.
   
   Dead code removal:
   
       jl_uv.c: jl_bufptr(), jl_ios_buf_base(), jl_putc(), jl_pututf8()
       sys.c: jl_ios_size()
   
   New jl_safe_printf().
   
   jl_safe_printf() uses a statically allocated 1000 byte buffer to
   vnsprintf() a message then calls write(2) to send it to stderr.
   
   jl_safe_printf() is intended to be used in places where there is the
   potential for out of memory, corrupted stack, re-entrancy etc.
   
   The current jl_safe_printf() implementation is not 100% safe in all
   situations, but it should be pretty good most of the time, especially
   if the formatting is limited to %d.
   
   The safety of jl_safe_printf() could be improved later, but at least
   for now the places were safety might matter are identified by its use.
   
   jl_safe_printf() is used in:
   
    - sigdie_handler()
    - sigint_handler()
    - _exception_handler()
    - catch_exception_raise()
    - gdblookup()
   
   Thanks to @vtjnash for assistance and feedback with these changes.
   
   Dead code cleanup & jl_write() simplificaiton.
   
   Clean up dead code:
       stream.jl : write!() — My apologies if this is used somewhere, I
   could’t find any doc or callers.
       builtins.c : jl_print_symbol(), jl_print_int64()
       ccall.cpp : if(0 …) jl_puts()
       jl_uv.c : jl_puts
   
   Replace 2 remaining calls to jl_puts() with calls to jl_printf() for
   consistency.
       builtins.c : jl_error()
       repl.c : true_main()
   
   Move jl_uv_writecb() implementation from stream.jl to jl_uv.c.
   This callback is only used by jl_write(),
   which is only called from jl_vprintf() in runtime C code.
   This helps to de-tangle fs.jl and stream.jl from the runtime's printf().
   
   Use jl_safe_printf() to attempt error message output in jl_uv_writecb().
   If this callback is printing an error, there was a problem writing to
   JL_STDOUT or JL_STDERR, so its best to try the simpelest means possible
   to get the error out.
   
   update doc/devdocs/stdio.rst to remove reference to:
       jl_write(), jl_putc(), jl_puts().
   
   Simplify handling of STDOUT and STDERR early in initialisation:
       Instead of calling fwrite(), just call uv_default_loop() to get the
       jl_io_loop and then call jl_fs_write as usual.
       This means that all jl_printf()s now go through uvlib.
       There is a chance that this won’t work in win32, AppVeyor will tell...
   
   Remove C interface for single character writes:
   
    - jl_fs_write_byte()
    - jl_putc_copy()
    - jl_pututf8_copy()
   
   Hadnle single character writes in Julia:
   
    - write(f::File,        c::UInt8) = write(f, [c])
    - write(s::AsyncStream, b::UInt8) = write(s, [b])
    - write(s::AsyncStream, c::Char)  = write(s, string(c))
   
   Rationale:
   
    - Writing to a libuv stream involves: "Julia does C malloc, Julia calls C,
      C calls libuv, libuv calls C callback, C callback calls julia hook,
      C callcback does c_free". Having less special cases of this makes
      it easier to reason about correctness.
   
    - Whatever overhead there might be in creating the temporary 1
      element array (or string); it is small compared to all the
      machinery in libuv, and the OS that actually makes the single
      character write happen.
   
    - If a user is doing single character writes to a libuv stream,
      they either don’t care about performance, or they should be
      buffering in Julia before calling write().
   
   Inline jl_write_copy() into only remaining called: jl_write():
   
    - This is now the only place that needs to know about the
      trick used to store a copy of the output string after the
      request struct (i.e. malloc(sizeof(uv_write_t) + n));
   
   Removed dead code:
    - stream.jl : make_stdout_stream()
    - stream.jl : jl_write_copy()
   
   Rename:
    - jl_write_no_copy() -> jl_uv_write()
   
   Move common code from stream.jl write() functions into uv_write macro:
    - ccall to jl_uv_write() (was jl_write_no_copy).
    - wait for current task
   
   Simplify uv_write memory management:
   
   Try to keep all the state management in one place (in macto uv_write()).
   
   Move free() of uv_write_t request object
   from C callback jl_uv_writecb_task() to macro uv_write().
   This puts the malloc() and the free() in the same place.
   
   Move uv_req_set_data(uvw,C_NULL) from C jl_uv_write() to macro
   uv_write().
   In _uv_hook_writecb_task() assert that uv_req_data(req) is not NULL.
   libuv should not call the callback from within the call to uv_write(),
   libuv has an internal “write_completed_queue” that is pumped by the main
   loop.

   

   samoconnor committed Feb 10, 2015
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2. Refinement per @vtjnash comments. …

   Make uv_write() a function (was a macro) and do c_free in "finally" clause.
   
   Explicit null-termination in jl_safe_printf() to allow for win32's
   non-posix vsnprintf behaviour. See also JuliaLang#9624.
   
   Use jl_safe_printf() in profile thread.
   
   Send help message to jl_printf(JL_STDOUT,)  was stderr.

   

   samoconnor committed Feb 10, 2015
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