Hi Morten,
From: Konstantin Ananyev [mailto:konstantin.v.anan...@yandex.ru]
Sent: Friday, 6 May 2022 21.38
05/05/2022 08:11, Tyler Retzlaff пишет:
On Wed, May 04, 2022 at 11:55:57PM +0100, Konstantin Ananyev wrote:
04/05/2022 16:46, Tyler Retzlaff пишет:
Provide a portable type-safe thread identifier.
Provide rte_thread_self for obtaining current thread identifier.
Signed-off-by: Narcisa Vasile <navas...@microsoft.com>
Signed-off-by: Tyler Retzlaff <roret...@linux.microsoft.com>
Acked-by: Dmitry Kozlyuk <dmitry.kozl...@gmail.com>
---
lib/eal/include/rte_thread.h | 22 ++++++++++++++++++++++
lib/eal/unix/rte_thread.c | 11 +++++++++++
lib/eal/version.map | 3 +++
lib/eal/windows/rte_thread.c | 10 ++++++++++
4 files changed, 46 insertions(+)
diff --git a/lib/eal/include/rte_thread.h
b/lib/eal/include/rte_thread.h
index 8be8ed8..14478ba 100644
--- a/lib/eal/include/rte_thread.h
+++ b/lib/eal/include/rte_thread.h
@@ -1,7 +1,10 @@
/* SPDX-License-Identifier: BSD-3-Clause
* Copyright(c) 2021 Mellanox Technologies, Ltd
+ * Copyright (C) 2022 Microsoft Corporation
*/
+#include <stdint.h>
+
#include <rte_os.h>
#include <rte_compat.h>
@@ -21,10 +24,29 @@
#endif
/**
+ * Thread id descriptor.
+ */
+typedef struct {
+ uintptr_t opaque_id; /**< thread identifier */
I know that currently on linux typeof(pthread_id) == unsigned long
int.
Though wouldn't it be safer and cleaner to use pthread_t explicitly
on posix-like systems?
i believe the previous discussions are.
* preference for reduced or no conditional compilation.
* preference for sizeof(type) to be `the same' on all platforms.
It would be the same as long as sizes of pthread_t uintptr_t are equal.
They are not. pthread_t (Linux thread ID) and DWORD (Windows thread ID) are
both 32 bit, uintptr_t is 64 or 32 bit depending on pointer size (32 or 64 bit
CPU).
What make you think pthread_t is 32-bit on linux?
From <pthread.h> on my box:
typedef unsigned long int pthread_t;
So it is either 64-bit or 32-bit depending on arch.
Same as uintptr_t.
* preference for platform agnostic headers. i.e. don't drag
platform specific headers into the application namespace when
including rte_xxx.h headers.
Something like:
typedef struct {
#ifdef WINDOWS
uintptr_t opaque_id;
#else
pthread_t opaque_id;
#endif
};
AFAIK POSIX itself doesn't require pthread_t to be an 'arithmetic
type'.
yes, this is correct. newer posix introduced this to allow the use of
structs. i assume prior reviewers are aware of the recent posix
standard (or should be).
this type makes no attempt to be usable on platforms that use
a handle > sizeof(uintptr_t). though any platform that does is free
to shove a pointer to struct into the handle at the cost of a
dereference if that is their implementation.
Using pthread_t directly still seems like a safest bet to me.
Then we can avoid doing these explicit type conversions before/after
each pthread_xxx() call and wouldn't need to worry if we'll ever have
platform with bigger pthread_t (though yes, I admit it is very
unlikely).
But, if we still prefer to go ahead with 'arch-neutral' approach,
then I think we need to have compilation time check that opaque_id
is big enough to hold pthread_t value:
RTE_BUILD_BUG_ON(sizeof(pthread_t) != sizeof(opaque_id)) or so.
I agree with Konstantin's concerns. All this type casting increases the risk
for bugs. Also, I don't understand the need to use a 64 bit value when thread
IDs are 32 bit in both Linux and Windows.
The thread handling is O/S specific code, so #ifdef is unavoidable.
Furthermore, I don't think we should wrap O/S specific integer types into
structs - it adds unnecessary complexity.
I would prefer:
#ifdef WINDOWS
typedef DWORD rte_thread_t;
#else
typedef pthread_t rte_thread_t;
#endif
+} rte_thread_t;
+
+/**
* TLS key type, an opaque pointer.
*/
typedef struct eal_tls_key *rte_thread_key;
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Get the id of the calling thread.
+ *
+ * @return
+ * Return the thread id of the calling thread.
+ */
+__rte_experimental
+rte_thread_t rte_thread_self(void);
+
#ifdef RTE_HAS_CPUSET
/**
diff --git a/lib/eal/unix/rte_thread.c b/lib/eal/unix/rte_thread.c
index c34ede9..82e008f 100644
--- a/lib/eal/unix/rte_thread.c
+++ b/lib/eal/unix/rte_thread.c
@@ -1,5 +1,6 @@
/* SPDX-License-Identifier: BSD-3-Clause
* Copyright 2021 Mellanox Technologies, Ltd
+ * Copyright (C) 2022 Microsoft Corporation
*/
#include <errno.h>
@@ -15,6 +16,16 @@ struct eal_tls_key {
pthread_key_t thread_index;
};
+rte_thread_t
+rte_thread_self(void)
+{
+ rte_thread_t thread_id;
+
+ thread_id.opaque_id = (uintptr_t)pthread_self();
+
+ return thread_id;
+}
+
int
rte_thread_key_create(rte_thread_key *key, void
(*destructor)(void *))
{
diff --git a/lib/eal/version.map b/lib/eal/version.map
index b53eeb3..05ce8f9 100644
--- a/lib/eal/version.map
+++ b/lib/eal/version.map
@@ -420,6 +420,9 @@ EXPERIMENTAL {
rte_intr_instance_free;
rte_intr_type_get;
rte_intr_type_set;
+
+ # added in 22.07
+ rte_thread_self;
};
INTERNAL {
diff --git a/lib/eal/windows/rte_thread.c
b/lib/eal/windows/rte_thread.c
index 667287c..59fed3c 100644
--- a/lib/eal/windows/rte_thread.c
+++ b/lib/eal/windows/rte_thread.c
@@ -11,6 +11,16 @@ struct eal_tls_key {
DWORD thread_index;
};
+rte_thread_t
+rte_thread_self(void)
+{
+ rte_thread_t thread_id;
+
+ thread_id.opaque_id = GetCurrentThreadId();
+
+ return thread_id;
+}
+
int
rte_thread_key_create(rte_thread_key *key,
__rte_unused void (*destructor)(void *))
