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-rw-r--r--absl/base/internal/spinlock_akaros.inc35
-rw-r--r--absl/base/internal/spinlock_wait.cc2
-rw-r--r--absl/base/internal/sysinfo.cc24
3 files changed, 61 insertions, 0 deletions
diff --git a/absl/base/internal/spinlock_akaros.inc b/absl/base/internal/spinlock_akaros.inc
new file mode 100644
index 00000000..051c8cf8
--- /dev/null
+++ b/absl/base/internal/spinlock_akaros.inc
@@ -0,0 +1,35 @@
+// Copyright 2017 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// This file is an Akaros-specific part of spinlock_wait.cc
+
+#include <atomic>
+
+#include "absl/base/internal/scheduling_mode.h"
+
+extern "C" {
+
+ABSL_ATTRIBUTE_WEAK void AbslInternalSpinLockDelay(
+ std::atomic<uint32_t>* /* lock_word */, uint32_t /* value */,
+ int /* loop */, absl::base_internal::SchedulingMode /* mode */) {
+ // In Akaros, one must take care not to call anything that could cause a
+ // malloc(), a blocking system call, or a uthread_yield() while holding a
+ // spinlock. Our callers assume will not call into libraries or other
+ // arbitrary code.
+}
+
+ABSL_ATTRIBUTE_WEAK void AbslInternalSpinLockWake(
+ std::atomic<uint32_t>* /* lock_word */, bool /* all */) {}
+
+} // extern "C"
diff --git a/absl/base/internal/spinlock_wait.cc b/absl/base/internal/spinlock_wait.cc
index 0fd36286..8f951b66 100644
--- a/absl/base/internal/spinlock_wait.cc
+++ b/absl/base/internal/spinlock_wait.cc
@@ -23,6 +23,8 @@
#if defined(_WIN32)
#include "absl/base/internal/spinlock_win32.inc"
+#elif defined(__akaros__)
+#include "absl/base/internal/spinlock_akaros.inc"
#else
#include "absl/base/internal/spinlock_posix.inc"
#endif
diff --git a/absl/base/internal/sysinfo.cc b/absl/base/internal/sysinfo.cc
index 9e0140fa..00e98b66 100644
--- a/absl/base/internal/sysinfo.cc
+++ b/absl/base/internal/sysinfo.cc
@@ -284,6 +284,30 @@ pid_t GetTID() {
return syscall(SYS_gettid);
}
+#elif defined(__akaros__)
+
+pid_t GetTID() {
+ // Akaros has a concept of "vcore context", which is the state the program
+ // is forced into when we need to make a user-level scheduling decision, or
+ // run a signal handler. This is analogous to the interrupt context that a
+ // CPU might enter if it encounters some kind of exception.
+ //
+ // There is no current thread context in vcore context, but we need to give
+ // a reasonable answer if asked for a thread ID (e.g., in a signal handler).
+ // Thread 0 always exists, so if we are in vcore context, we return that.
+ //
+ // Otherwise, we know (since we are using pthreads) that the uthread struct
+ // current_uthread is pointing to is the first element of a
+ // struct pthread_tcb, so we extract and return the thread ID from that.
+ //
+ // TODO(dcross): Akaros anticipates moving the thread ID to the uthread
+ // structure at some point. We should modify this code to remove the cast
+ // when that happens.
+ if (in_vcore_context())
+ return 0;
+ return reinterpret_cast<struct pthread_tcb *>(current_uthread)->id;
+}
+
#else
// Fallback implementation of GetTID using pthread_getspecific.