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From: Serge Petrenko via Tarantool-patches <tarantool-patches@dev.tarantool.org>
To: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>,
	tarantool-patches@dev.tarantool.org, gorcunov@gmail.com
Subject: Re: [Tarantool-patches] [PATCH 06/16] cord_buf: introduce ownership management
Date: Mon, 22 Mar 2021 19:48:03 +0300	[thread overview]
Message-ID: <fc58cdb8-54a0-ec10-a8e3-e59345d0dfdd@tarantool.org> (raw)
In-Reply-To: <eeb753ae3c035238444a76af01afbfcc532794ec.1616200860.git.v.shpilevoy@tarantool.org>



20.03.2021 03:42, Vladislav Shpilevoy пишет:
> The global ibuf used for hot Lua and Lua C code didn't have
> ownership management. As a result, it could be reused in some
> unexpected ways during Lua GC via __gc handlers, even if it was
> currently in use in some code below the stack.
>
> The patch makes cord_ibuf_take() steal the global buffer from its
> global stash, and assign to the current fiber. cord_ibuf_put()
> puts it back to the stash, and detaches from the fiber. If yield
> happens before cord_ibuf_put(), the buffer is detached
> automatically.
>
> Fiber attach/detach is done via on_yield/on_stop triggers. The
> buffer is not supposed to survive a yield, so this allows to
> free/put the buffer back to the stash even if the owner didn't do
> that. For instance, if a Lua exception was raised before
> cord_ibuf_put() was called.
>
> This makes cord buffer being safe to use in any yield-free code,
> even if Lua GC might be started. And in non-Lua code as well.
>
> Part of #5632
> ---
>   src/lib/core/cord_buf.c      | 150 +++++++++++++++++++++++++++++++----
>   src/lib/core/cord_buf.h      |   6 +-
>   test/app-tap/buffer.test.lua |  59 ++++++++++++++
>   3 files changed, 199 insertions(+), 16 deletions(-)
>   create mode 100755 test/app-tap/buffer.test.lua
>
> diff --git a/src/lib/core/cord_buf.c b/src/lib/core/cord_buf.c
> index cac508c3d..9450d75bc 100644
> --- a/src/lib/core/cord_buf.c
> +++ b/src/lib/core/cord_buf.c
> @@ -5,6 +5,7 @@
>    */
>   #include "cord_buf.h"
>   #include "fiber.h"
> +#include "trigger.h"
>   
>   #include "small/ibuf.h"
>   
> @@ -13,35 +14,154 @@ enum {
>   	CORD_IBUF_START_CAPACITY = 16384,
>   };
>   
> -static struct ibuf *cord_buf_global = NULL;
> +/** Global buffer with automatic collection on fiber yield. */
> +struct cord_buf {
> +	/** Base buffer. */
> +	struct ibuf base;
> +	/**
> +	 * Triggers on fiber stop/yield when the buffer is either destroyed or
> +	 * cached to the global stash for later reuse.
> +	 */
> +	struct trigger on_stop;
> +	struct trigger on_yield;
> +#if !NDEBUG

Shouldn't it be `#if !defined(NDEBUG)`? I'm not sure, just asking.


-- 
Serge Petrenko


  reply	other threads:[~2021-03-22 16:48 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-20  0:42 [Tarantool-patches] [PATCH 00/16] Cord buffer, static alloc, and Lua GC bug Vladislav Shpilevoy via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 01/16] fio: don't use shared buffer in pread() Vladislav Shpilevoy via Tarantool-patches
2021-03-22  7:19   ` Cyrill Gorcunov via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 10/16] uri: replace static_alloc with ffi stash and ibuf Vladislav Shpilevoy via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 11/16] buffer: remove static_alloc() from Lua Vladislav Shpilevoy via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 12/16] lua: use lua_pushfstring() instead of tt_sprintf() Vladislav Shpilevoy via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 13/16] sio: rework sio_strfaddr() Vladislav Shpilevoy via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 14/16] sio: increase SERVICE_NAME_MAXLEN size Vladislav Shpilevoy via Tarantool-patches
2021-03-21 21:58   ` Cyrill Gorcunov via Tarantool-patches
2021-03-22 22:32     ` Vladislav Shpilevoy via Tarantool-patches
2021-03-23  6:56       ` Cyrill Gorcunov via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 15/16] sio: introduce and use sio_snprintf() Vladislav Shpilevoy via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 16/16] buffer: remove Lua registers Vladislav Shpilevoy via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 02/16] test: don't use IBUF_SHARED in the tests Vladislav Shpilevoy via Tarantool-patches
2021-03-22  7:35   ` Cyrill Gorcunov via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 03/16] tuple: pass global ibuf explicitly where possible Vladislav Shpilevoy via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 04/16] iconv: take errno before reseting the context Vladislav Shpilevoy via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 05/16] cord_buf: introduce cord_buf API Vladislav Shpilevoy via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 06/16] cord_buf: introduce ownership management Vladislav Shpilevoy via Tarantool-patches
2021-03-22 16:48   ` Serge Petrenko via Tarantool-patches [this message]
2021-03-22 22:32     ` Vladislav Shpilevoy via Tarantool-patches
2021-03-23  7:46       ` Serge Petrenko via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 07/16] buffer: implement ffi stash Vladislav Shpilevoy via Tarantool-patches
2021-03-23  0:29   ` Vladislav Shpilevoy via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 08/16] uuid: replace static_alloc with " Vladislav Shpilevoy via Tarantool-patches
2021-03-20  0:42 ` [Tarantool-patches] [PATCH 09/16] uuid: drop tt_uuid_str() from Lua Vladislav Shpilevoy via Tarantool-patches
2021-03-21 16:38 ` [Tarantool-patches] [PATCH 00/16] Cord buffer, static alloc, and Lua GC bug Vladislav Shpilevoy via Tarantool-patches
2021-03-22  7:52 ` Cyrill Gorcunov via Tarantool-patches
2021-03-22  7:56 ` Konstantin Osipov via Tarantool-patches
2021-03-22 17:17 ` Serge Petrenko via Tarantool-patches
2021-03-23 23:45 ` Vladislav Shpilevoy via Tarantool-patches
2021-03-24 13:28 ` Kirill Yukhin via Tarantool-patches

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