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

[Sergey Kaplun <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