Re: [Tarantool-patches] [PATCH v2 1/1] fiber: extend max fiber name length to 255

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

Nikita, please, do a second review.

On 15/03/2020 16:11, Vladislav Shpilevoy wrote:
> Users keep complaining about too short fiber name. New limit is
> 255, should be enough for any sane name.
> 
> Closes #4394
> 
> @TarantoolBot document
> Title: fiber.name length limit.
> 
> It was 32, now it is 255. Besides, it seems like `fiber.name`
> `{truncate = true}` option is not documented.
> 
> By default, if a new name is too long, `fiber.name(new_name)`
> fails with an exception. To make it always succeed there is an
> option 'truncate': `fiber.name(new_name, {truncate = true})`. It
> truncates the name to the max length if it is too long.
> ---
> Branch: http://github.com/tarantool/tarantool/tree/gerold103/gh-4394-fiber-name-inline
> Issue: https://github.com/tarantool/tarantool/issues/4394
> 
> Changes in v2:
> - Short fiber names are kept inside struct fiber.
> 
>  src/lib/core/fiber.c    | 28 ++++++++++++++++++++++++++--
>  src/lib/core/fiber.h    | 14 +++++++++++---
>  test/app/fiber.result   |  8 ++++----
>  test/app/fiber.test.lua |  2 +-
>  test/unit/fiber.cc      |  6 +++---
>  test/unit/fiber.result  |  2 +-
>  6 files changed, 46 insertions(+), 14 deletions(-)
> 
> diff --git a/src/lib/core/fiber.c b/src/lib/core/fiber.c
> index ada7972cb..359ef1187 100644
> --- a/src/lib/core/fiber.c
> +++ b/src/lib/core/fiber.c
> @@ -912,8 +912,26 @@ fiber_loop(MAYBE_UNUSED void *data)
>  void
>  fiber_set_name(struct fiber *fiber, const char *name)
>  {
> -	assert(name != NULL);
> -	snprintf(fiber->name, sizeof(fiber->name), "%s", name);
> +	size_t len = strlen(name);
> +	if (len <= FIBER_NAME_INLINE) {
> +		if (fiber->name != fiber->inline_name) {
> +			free(fiber->name);
> +			fiber->name = fiber->inline_name;
> +		}
> +	} else {
> +		if (len > FIBER_NAME_MAX)
> +			len = FIBER_NAME_MAX;
> +		char *new_name;
> +		if (fiber->name != fiber->inline_name)
> +			new_name = realloc(fiber->name, len + 1);
> +		else
> +			new_name = malloc(len + 1);
> +		if (new_name == NULL)
> +			panic("fiber_set_name() failed with OOM");
> +		fiber->name = new_name;
> +	}
> +	memcpy(fiber->name, name, len);
> +	fiber->name[len] = 0;
>  }
>  
>  static inline void *
> @@ -1242,6 +1260,9 @@ fiber_destroy(struct cord *cord, struct fiber *f)
>  	region_destroy(&f->gc);
>  	fiber_stack_destroy(f, &cord->slabc);
>  	diag_destroy(&f->diag);
> +	if (f->name != f->inline_name)
> +		free(f->name);
> +	f->name = NULL;
>  }
>  
>  void
> @@ -1357,6 +1378,7 @@ cord_create(struct cord *cord, const char *name)
>  	fiber_reset(&cord->sched);
>  	diag_create(&cord->sched.diag);
>  	region_create(&cord->sched.gc, &cord->slabc);
> +	cord->sched.name = NULL;
>  	fiber_set_name(&cord->sched, "sched");
>  	cord->fiber = &cord->sched;
>  
> @@ -1405,6 +1427,8 @@ cord_destroy(struct cord *cord)
>  	}
>  	region_destroy(&cord->sched.gc);
>  	diag_destroy(&cord->sched.diag);
> +	if (cord->sched.name != cord->sched.inline_name)
> +		free(cord->sched.name);
>  	slab_cache_destroy(&cord->slabc);
>  }
>  
> diff --git a/src/lib/core/fiber.h b/src/lib/core/fiber.h
> index 8a3e5aef5..fedc37c87 100644
> --- a/src/lib/core/fiber.h
> +++ b/src/lib/core/fiber.h
> @@ -111,7 +111,10 @@ struct cpu_stat {
>  
>  #endif /* ENABLE_FIBER_TOP */
>  
> -enum { FIBER_NAME_MAX = 32 };
> +enum {
> +	FIBER_NAME_INLINE = 32,
> +	FIBER_NAME_MAX = 255
> +};
>  
>  /**
>   * Fiber ids [0; 100] are reserved.
> @@ -510,7 +513,12 @@ struct fiber {
>  	struct ipc_wait_pad *wait_pad;
>  	/** Exception which caused this fiber's death. */
>  	struct diag diag;
> -	char name[FIBER_NAME_MAX + 1];
> +	/**
> +	 * Name points at inline_name in case it is short. Long
> +	 * name is allocated on the heap.
> +	 */
> +	char *name;
> +	char inline_name[FIBER_NAME_INLINE + 1];
>  };
>  
>  /** Invoke on_stop triggers and delete them. */
> @@ -578,7 +586,7 @@ struct cord {
>  	struct slab_cache slabc;
>  	/** The "main" fiber of this cord, the scheduler. */
>  	struct fiber sched;
> -	char name[FIBER_NAME_MAX];
> +	char name[FIBER_NAME_INLINE + 1];
>  };
>  
>  extern __thread struct cord *cord_ptr;
> diff --git a/test/app/fiber.result b/test/app/fiber.result
> index 6d9604ad8..7331f61b3 100644
> --- a/test/app/fiber.result
> +++ b/test/app/fiber.result
> @@ -1186,7 +1186,7 @@ fiber = nil
>  ---
>  ...
>  --
> --- gh-2622, gh-4011: fiber.name() truncates new name.
> +-- gh-2622, gh-4011, gh-4394: fiber.name() truncates new name.
>  --
>  fiber = require('fiber')
>  ---
> @@ -1214,14 +1214,14 @@ fiber.name(long_name, {truncate = true})
>  ...
>  fiber.name()
>  ---
> -- aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
> +- aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
>  ...
>  f = fiber.self()
>  ---
>  ...
>  fiber.name(f)
>  ---
> -- aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
> +- aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
>  ...
>  fiber.name(f, 'new_name')
>  ---
> @@ -1239,7 +1239,7 @@ fiber.name(f, long_name, {truncate = true})
>  ...
>  fiber.name(f)
>  ---
> -- aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
> +- aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
>  ...
>  --
>  -- gh-3493 fiber.create() does not roll back memtx transaction
> diff --git a/test/app/fiber.test.lua b/test/app/fiber.test.lua
> index 6df210d9c..b8e9abc6e 100644
> --- a/test/app/fiber.test.lua
> +++ b/test/app/fiber.test.lua
> @@ -504,7 +504,7 @@ test_run:cmd("setopt delimiter ''");
>  fiber = nil
>  
>  --
> --- gh-2622, gh-4011: fiber.name() truncates new name.
> +-- gh-2622, gh-4011, gh-4394: fiber.name() truncates new name.
>  --
>  fiber = require('fiber')
>  long_name = string.rep('a', 300)
> diff --git a/test/unit/fiber.cc b/test/unit/fiber.cc
> index 91f7d43f9..b0dfc9b14 100644
> --- a/test/unit/fiber.cc
> +++ b/test/unit/fiber.cc
> @@ -171,9 +171,9 @@ fiber_name_test()
>  
>  	note("set new fiber name: %s.\n", fiber_name(fiber()));
>  
> -	const char *long_name = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
> -		"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"\
> -		"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
> +	char long_name[FIBER_NAME_MAX + 30];
> +	memset(long_name, 'a', sizeof(long_name));
> +	long_name[sizeof(long_name) - 1] = 0;
>  
>  	fiber_set_name(fiber(), long_name);
>  
> diff --git a/test/unit/fiber.result b/test/unit/fiber.result
> index 7c9f85dcd..a61e0a2b8 100644
> --- a/test/unit/fiber.result
> +++ b/test/unit/fiber.result
> @@ -5,7 +5,7 @@ SystemError Failed to allocate 42 bytes in allocator for exception: Cannot alloc
>  
>  # set new fiber name: Horace.
>  
> -# fiber name is truncated: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.
> +# fiber name is truncated: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa.
>  
>  	*** fiber_name_test: done ***
>  	*** fiber_join_test ***
>