Re: [Tarantool-patches] [PATCH luajit v2 6/7] misc: add Lua API for memory profiler

["Sergey Ostanevich" <sergos@tarantool.org>]

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LGTM

Best regards,
Sergos 

Sunday, 27 December 2020, 16:43 +0300 from skaplun@tarantool.org  <skaplun@tarantool.org>:
>
>Hi!
>
>Thanks for the review!
>
>On 27.12.20, Sergey Ostanevich wrote:
>> Hi!
>> 
>> Thanks for the patch!
>> 
>> 2 nits below, LGTM after the fix.
>> 
>> Sergos
>> 
>> 
>> > On 25 Dec 2020, at 18:26, Sergey Kaplun < skaplun@tarantool.org > wrote:
>> > 
>> > This patch introduces Lua API for LuaJIT memory profiler implemented in
>> > the scope of the previous patch.
>> > 
>> > Profiler returns some true value if started/stopped successfully,
>> > returns nil on failure (plus an error message as a second result and a
>> > system-dependent error code as a third result).
>> > If LuaJIT build without memory profiler both return `false`.
>>            ^^^^^^ was built
>
>Changed to `is build`.
>
>> > 
>> > <lj_errmsg.h> have adjusted with two new errors
>> > PROF_ISRUNNING/PROF_NOTRUNNING returned in case when profiler has
>> > started/stopped already correspondingly.
>> > 
>> > Part of tarantool/tarantool#5442
>> > ---
>> > 
>> > Changes in v2:
>> >  - Added pushing of errno for ERR_PROF* and ERRMEM
>> >  - Added forgotten assert.
>> > 
>> > src/Makefile.dep |   5 +-
>> > src/lib_misc.c   | 167 +++++++++++++++++++++++++++++++++++++++++++++++
>> > src/lj_errmsg.h  |   6 ++
>> > 3 files changed, 176 insertions(+), 2 deletions(-)
>> > 
>> > diff --git a/src/Makefile.dep b/src/Makefile.dep
>> > index 8ae14a5..c3d0977 100644
>> > --- a/src/Makefile.dep
>> > +++ b/src/Makefile.dep
>> > @@ -29,8 +29,9 @@ lib_jit.o: lib_jit.c lua.h luaconf.h lauxlib.h lualib.h lj_obj.h lj_def.h \
>> >  lj_vm.h lj_vmevent.h lj_lib.h luajit.h lj_libdef.h
>> > lib_math.o: lib_math.c lua.h luaconf.h lauxlib.h lualib.h lj_obj.h \
>> >  lj_def.h lj_arch.h lj_lib.h lj_vm.h lj_libdef.h
>> > -lib_misc.o: lib_misc.c lua.h luaconf.h lmisclib.h lj_obj.h lj_def.h lj_arch.h \
>> > - lj_str.h lj_tab.h lj_lib.h lj_libdef.h
>> > +lib_misc.o: lib_misc.c lua.h luaconf.h lmisclib.h lauxlib.h lj_obj.h \
>> > + lj_def.h lj_arch.h lj_str.h lj_tab.h lj_lib.h lj_gc.h lj_err.h \
>> > + lj_errmsg.h lj_memprof.h lj_libdef.h
>> > lib_os.o: lib_os.c lua.h luaconf.h lauxlib.h lualib.h lj_obj.h lj_def.h \
>> >  lj_arch.h lj_gc.h lj_err.h lj_errmsg.h lj_buf.h lj_str.h lj_lib.h \
>> >  lj_libdef.h
>> > diff --git a/src/lib_misc.c b/src/lib_misc.c
>> > index 6f7b9a9..36fe29f 100644
>> > --- a/src/lib_misc.c
>> > +++ b/src/lib_misc.c
>> > @@ -8,13 +8,21 @@
>> > #define lib_misc_c
>> > #define LUA_LIB
>> > 
>> > +#include <stdio.h>
>> > +#include <errno.h>
>> > +
>> > #include "lua.h"
>> > #include "lmisclib.h"
>> > +#include "lauxlib.h"
>> > 
>> > #include "lj_obj.h"
>> > #include "lj_str.h"
>> > #include "lj_tab.h"
>> > #include "lj_lib.h"
>> > +#include "lj_gc.h"
>> > +#include "lj_err.h"
>> > +
>> > +#include "lj_memprof.h"
>> > 
>> > /* ------------------------------------------------------------------------ */
>> > 
>> > @@ -67,8 +75,167 @@ LJLIB_CF(misc_getmetrics)
>> > 
>> > #include "lj_libdef.h"
>> > 
>> > +/* ----- misc.memprof module ---------------------------------------------- */
>> > +
>> > +#define LJLIB_MODULE_misc_memprof
>> > +
>> > +/*
>> > +** Yep, 8Mb. Tuned in order not to bother the platform with too often flushes.
>> > +*/
>> > +#define STREAM_BUFFER_SIZE (8 * 1024 * 1024)
>> > +
>> > +/* Structure given as ctx to memprof writer and on_stop callback. */
>> > +struct memprof_ctx {
>> > +  /* Output file stream for data. */
>> > +  FILE *stream;
>> > +  /* Profiled global_State for lj_mem_free at on_stop callback. */
>> > +  global_State *g;
>> > +};
>> > +
>> > +static LJ_AINLINE void memprof_ctx_free(struct memprof_ctx *ctx, uint8_t *buf)
>> > +{
>> > +  lj_mem_free(ctx->g, buf, STREAM_BUFFER_SIZE);
>> > +  lj_mem_free(ctx->g, ctx, sizeof(*ctx));
>> > +}
>> > +
>> > +/* Default buffer writer function. Just call fwrite to corresponding FILE. */
>> > +static size_t buffer_writer_default(const void **buf_addr, size_t len,
>> > +				    void *opt)
>> > +{
>> > +  FILE *stream = ((struct memprof_ctx *)opt)->stream;
>> > +  const void * const buf_start = *buf_addr;
>> > +  const void *data = *buf_addr;
>> > +  size_t write_total = 0;
>> > +
>> > +  lua_assert(len <= STREAM_BUFFER_SIZE);
>> > +
>> > +  for (;;) {
>> > +    const size_t written = fwrite(data, 1, len, stream);
>> > +
>> > +    if (LJ_UNLIKELY(written == 0)) {
>> > +      /* Re-tries write in case of EINTR. */
>> > +      if (errno == EINTR) {
>> > +	errno = 0;
>> > +	continue;
>> > +      }
>> > +      break;
>> > +    }
>> > +
>> > +    write_total += written;
>> > +
>> > +    if (write_total == len)
>> > +      break;
>> > +
>> > +    data = (uint8_t *)data + (ptrdiff_t)written;
>> 
>> After incomplete write you’ll return to the fwrite() call with
>> data pointer moved, but with len untouched -> you’ll read beyond
>> the buffer.
>
>Oh! I keep stepping on the same rake...
>Thank you very much! Fixed!
>
>See the iterative patch below. Branch is force pushed.
>
>> 
>> > +  }
>> > +  lua_assert(write_total <= len);
>> > +
>> > +  *buf_addr = buf_start;
>> > +  return write_total;
>> > +}
>> > +
>> > +/* Default on stop callback. Just close corresponding stream. */
>> > +static int on_stop_cb_default(void *opt, uint8_t *buf)
>> > +{
>> > +  struct memprof_ctx *ctx = opt;
>> > +  FILE *stream = ctx->stream;
>> > +  memprof_ctx_free(ctx, buf);
>> > +  return fclose(stream);
>> > +}
>> > +
>> > +/* local started, err, errno = misc.memprof.start(fname) */
>> > +LJLIB_CF(misc_memprof_start)
>> > +{
>> > +  struct lua_Prof_options opt = {0};
>> > +  struct memprof_ctx *ctx;
>> > +  const char *fname;
>> > +  int memprof_status;
>> > +  int started;
>> > +
>> > +  fname = strdata(lj_lib_checkstr(L, 1));
>> > +
>> > +  ctx = lj_mem_new(L, sizeof(*ctx));
>> > +  if (ctx == NULL)
>> > +    goto errmem;
>> > +
>> > +  opt.ctx = ctx;
>> > +  opt.writer = buffer_writer_default;
>> > +  opt.on_stop = on_stop_cb_default;
>> > +  opt.len = STREAM_BUFFER_SIZE;
>> > +  opt.buf = (uint8_t *)lj_mem_new(L, STREAM_BUFFER_SIZE);
>> > +  if (NULL == opt.buf) {
>> > +    lj_mem_free(G(L), ctx, sizeof(*ctx));
>> > +    goto errmem;
>> > +  }
>> > +
>> > +  ctx->g = G(L);
>> > +  ctx->stream = fopen(fname, "wb");
>> > +
>> > +  if (ctx->stream == NULL) {
>> > +    memprof_ctx_free(ctx, opt.buf);
>> > +    return luaL_fileresult(L, 0, fname);
>> > +  }
>> > +
>> > +  memprof_status = lj_memprof_start(L, &opt);
>> > +  started = memprof_status == PROFILE_SUCCESS;
>> > +
>> > +  if (LJ_UNLIKELY(!started)) {
>> > +    fclose(ctx->stream);
>> > +    remove(fname);
>> > +    memprof_ctx_free(ctx, opt.buf);
>> > +    switch (memprof_status) {
>> > +    case PROFILE_ERRRUN:
>> > +      lua_pushnil(L);
>> > +      lua_pushstring(L, err2msg(LJ_ERR_PROF_ISRUNNING));
>> > +      lua_pushinteger(L, EINVAL);
>> > +      return 3;
>> > +    case PROFILE_ERRIO:
>> > +      return luaL_fileresult(L, 0, fname);
>> > +    default:
>> > +      lua_assert(0);
>> > +      break;
>> > +    }
>> > +  }
>> > +  lua_pushboolean(L, started);
>> > +
>> > +  return 1;
>> > +errmem:
>> > +  lua_pushnil(L);
>> > +  lua_pushstring(L, err2msg(LJ_ERR_ERRMEM));
>> > +  lua_pushinteger(L, ENOMEM);
>> > +  return 3;
>> > +}
>> > +
>> > +/* local stopped, err, errno = misc.memprof.stop() */
>> > +LJLIB_CF(misc_memprof_stop)
>> > +{
>> > +  int status = lj_memprof_stop();
>> > +  int stopped_successfully = status == PROFILE_SUCCESS;
>> > +  if (!stopped_successfully) {
>> > +    switch (status) {
>> > +    case PROFILE_ERRRUN:
>> > +      lua_pushnil(L);
>> > +      lua_pushstring(L, err2msg(LJ_ERR_PROF_NOTRUNNING));
>> > +      lua_pushinteger(L, EINVAL);
>> > +      return 3;
>> > +    case PROFILE_ERRIO:
>> > +      return luaL_fileresult(L, 0, NULL);
>> > +    default:
>> > +      lua_assert(0);
>> > +      break;
>> > +    }
>> > +  }
>> > +  lua_pushboolean(L, stopped_successfully);
>> > +  return 1;
>> > +}
>> > +
>> > +#include "lj_libdef.h"
>> > +
>> > +/* ------------------------------------------------------------------------ */
>> > +
>> > LUALIB_API int luaopen_misc(struct lua_State *L)
>> > {
>> >   LJ_LIB_REG(L, LUAM_MISCLIBNAME, misc);
>> > +  LJ_LIB_REG(L, LUAM_MISCLIBNAME ".memprof", misc_memprof);
>> >   return 1;
>> > }
>> > diff --git a/src/lj_errmsg.h b/src/lj_errmsg.h
>> > index de7b867..6816da2 100644
>> > --- a/src/lj_errmsg.h
>> > +++ b/src/lj_errmsg.h
>> > @@ -185,6 +185,12 @@ ERRDEF(FFI_NYIPACKBIT,	"NYI: packed bit fields")
>> > ERRDEF(FFI_NYICALL,	"NYI: cannot call this C function (yet)")
>> > #endif
>> > 
>> > +#if LJ_HASPROFILE || LJ_HASMEMPROF
>> > +/* Profiler errors. */
>> > +ERRDEF(PROF_ISRUNNING,	"profiler is running already")
>> > +ERRDEF(PROF_NOTRUNNING,	"profiler is not running")
>> > +#endif
>> > +
>> > #undef ERRDEF
>> > 
>> > /* Detecting unused error messages:
>> > -- 
>> > 2.28.0
>> > 
>> 
>
>===================================================================
>diff --git a/src/lib_misc.c b/src/lib_misc.c
>index 36fe29f..f69f933 100644
>--- a/src/lib_misc.c
>+++ b/src/lib_misc.c
>@@ -110,7 +110,7 @@ static size_t buffer_writer_default(const void **buf_addr, size_t len,
>   lua_assert(len <= STREAM_BUFFER_SIZE);
> 
>   for (;;) {
>-    const size_t written = fwrite(data, 1, len, stream);
>+    const size_t written = fwrite(data, 1, len - write_total, stream);
> 
>     if (LJ_UNLIKELY(written == 0)) {
>       /* Re-tries write in case of EINTR. */
>@@ -122,13 +122,13 @@ static size_t buffer_writer_default(const void **buf_addr, size_t len,
>     }
> 
>     write_total += written;
>+    lua_assert(write_total <= len);
> 
>     if (write_total == len)
>       break;
> 
>     data = (uint8_t *)data + (ptrdiff_t)written;
>   }
>-  lua_assert(write_total <= len);
> 
>   *buf_addr = buf_start;
>   return write_total;
>===================================================================
>
>-- 
>Best regards,
>Sergey Kaplun

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