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

[Sergey Ostanevich <sergos@tarantool.org>]

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
> 
> <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.

> +  }
> +  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
>