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Commit a3c62f0c by Tobias Fuchs
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containers_cpp: fixes in LlxScx, added unit test for LlxScx

parent a425b12e
Inline Side-by-side
Showing with 116 additions and 158 deletions
containers_cpp/include/embb/containers/internal/fixed_size_list.h
......@@ -75,7 +75,7 @@ class FixedSizeList {
size_t capacity
/**< [IN] Capacity of the list */
);
/**
* Copy constructor.
*/
......
containers_cpp/include/embb/containers/internal/primitives/llx_scx-inl.h
......@@ -44,99 +44,8 @@ namespace embb {
namespace containers {
namespace primitives {
namespace internal {
#if 0
/**
* RAII-style implementation of a simplified hazard
* pointer scheme. SmartHazardPointer instances should
* reside only on the stack, never the heap, and T*
* values should reside only in the heap. A NodePtr can
* be automatically converted to a Node*, but an explicit
* constructor is needed to go the other way.
*
* Example:
* SmartHazardPointer<Node> shp = SmartHazardPointer(
* nodePool?>allocate());
* // assign via default copy constructor:
* *shp = Node(...);
*/
template< typename T >
class SmartHazardPointer {
public:
SmartHazardPointer(T ** node) {
while (true) {
ptr = *node;
table_->add(ptr);
// Full fence:
embb_atomic_memory_barrier();
T * reread = *node;
// @TODO: Prove practical wait-freedom
if (read == reread) {
return;
}
}
}
SmartHazardPointer(T * node) {
ptr = node;
}
/**
* Dereference operator.
*/
T * operator->() {
return ptr;
}
/**
* Dereference lvalue.
*/
T & operator*() {
return *ptr;
}
/**
* Equality test with regular pointer
*/
bool operator==(T * const other) {
return ptr == other;
}
/**
* Equality test with another SmartHazardPointer
*/
bool operator==(const SmartHazardPointer & other) {
return this->ptr == other->ptr;
}
/**
* Destructor, retires hazard pointer.
*/
~SmartHazardPointer() {
table_->remove(ptr);
}
/**
* Conversion to regular pointer.
*/
operator T*() {
return ptr;
}
private:
static HazardPointerTable * table_;
T * ptr;
};
#endif
} // namespace internal
template< class UserData >
unsigned int LlxScx<UserData>::ThreadId() {
template< typename UserData, typename ValuePool >
unsigned int LlxScx<UserData, ValuePool>::ThreadId() {
unsigned int thread_index;
int return_val = embb_internal_thread_index(&thread_index);
if (return_val != EMBB_SUCCESS)
......@@ -144,34 +53,33 @@ unsigned int LlxScx<UserData>::ThreadId() {
return thread_index;
}
template< class UserData >
LlxScx<UserData>::LlxScx(size_t max_links)
: max_links_(max_links) {
template< typename UserData, typename ValuePool >
LlxScx<UserData, ValuePool>::LlxScx(size_t max_links)
: max_links_(max_links),
max_threads_(embb::base::Thread::GetThreadsMaxCount()),
scx_record_list_pool_(max_threads_) {
typedef embb::containers::internal::FixedSizeList<LlxResult>
llx_result_list_t;
typedef embb::containers::internal::FixedSizeList<ScxRecord_t>
scx_record_list_t;
unsigned int num_threads = embb::base::Thread::GetThreadsMaxCount();
// Table in shared memory containing for each r in TryStoreConditional's
// dependent links, a copy of r's info value in this threads local table
// of LLX results.
scx_record_list_t empty_scx_list(3);
info_fields_ = static_cast<scx_record_list_t *>(
// Allocate a list of LLX results for every thread:
thread_llx_results_ = static_cast<llx_result_list_t *>(
embb::base::Allocation::AllocateCacheAligned(
num_threads * sizeof(empty_scx_list)));
max_threads_ * sizeof(llx_result_list_t)));
}
template< class UserData >
LlxScx<UserData>::~LlxScx() {
embb::base::Allocation::FreeAligned(info_fields_);
template< typename UserData, typename ValuePool >
LlxScx<UserData, ValuePool>::~LlxScx() {
embb::base::Allocation::FreeAligned(thread_llx_results_);
}
template< class UserData >
bool LlxScx<UserData>::TryLoadLinked(
template< typename UserData, typename ValuePool >
bool LlxScx<UserData, ValuePool>::TryLoadLinked(
DataRecord_t * const data_record,
DataRecord_t & user_data,
bool & finalized) {
finalized = false;
unsigned int thread_id = ThreadId();
// Order of initialization matters:
bool marked_1 = data_record->IsMarkedForFinalize();
ScxRecord_t * curr_scx = data_record->ScxInfo().Load();
......@@ -188,7 +96,7 @@ bool LlxScx<UserData>::TryLoadLinked(
llx_result.data_record = data_record;
llx_result.scx_record = curr_scx;
llx_result.user_data = user_data_local;
thread_llx_results_.Get().PushBack(llx_result);
thread_llx_results_[thread_id].PushBack(llx_result);
// Set return value:
user_data = user_data_local;
return true;
......@@ -210,15 +118,15 @@ bool LlxScx<UserData>::TryLoadLinked(
return false;
}
template< class UserData >
template< typename UserData, typename ValuePool >
template< typename FieldType >
bool LlxScx<UserData>::TryStoreConditional(
bool LlxScx<UserData, ValuePool>::TryStoreConditional(
embb::base::Atomic<FieldType> * field,
FieldType value,
embb::containers::internal::FixedSizeList<DataRecord_t *> & linked_deps,
embb::containers::internal::FixedSizeList<DataRecord_t *> & finalize_deps) {
typedef embb::containers::internal::FixedSizeList<DataRecord_t *> dr_list_t;
//typedef embb::containers::internal::FixedSizeList<ScxRecord_t *> op_list_t;
typedef embb::containers::internal::FixedSizeList<ScxRecord_t> scx_op_list_t;
// Preconditions:
// 1. For each r in linked_deps, this thread has performed an invocation
// I_r of LLX(r) linked to this SCX.
......@@ -228,17 +136,18 @@ bool LlxScx<UserData>::TryStoreConditional(
unsigned int thread_id = ThreadId();
// Let info_fields be a table in shared memory containing for each r in V,
// a copy of r's info value in this threads local table of LLX results:
info_fields_[thread_id].clear();
scx_op_list_t * info_fields = scx_record_list_pool_.Allocate(max_links_);
dr_list_t::const_iterator it;
dr_list_t::const_iterator end;
end = linked_deps.end();
// for each r in V ...
// for each r in linked_deps ...
for (it = linked_deps.begin(); it != end; ++it) {
// Find LLX result of r in thread-local table of LLX results:
typedef embb::containers::internal::FixedSizeList<LlxResult>
llx_result_list;
llx_result_list::iterator l_it = thread_llx_results_.Get().begin();
llx_result_list::iterator l_end = thread_llx_results_.Get().end();
llx_result_list::iterator l_it = thread_llx_results_[thread_id].begin();
llx_result_list::iterator l_end = thread_llx_results_[thread_id].end();
// Find LLX result of r in thread-local LLX results:
for (; l_it != l_end && l_it->data_record != *it; ++l_it);
if (l_it == l_end) {
// Missing LLX result for given linked data record, user did not
......@@ -246,9 +155,9 @@ bool LlxScx<UserData>::TryStoreConditional(
EMBB_THROW(embb::base::ErrorException,
"Missing preceding LLX on a data record used for SCX");
}
// ... copy of r's info value in this threads local table of LLX results
// Copy of r's info value in this threads local table of LLX results
ScxRecord_t scx_op(*(l_it->data_record->ScxInfo().Load()));
info_fields_[thread_id].PushBack(scx_op);
info_fields->PushBack(scx_op);
}
// Announce SCX operation. Lists linked_deps and finalize_dep are
// guaranteed to remain on the stack until this announced operation
......@@ -263,27 +172,27 @@ bool LlxScx<UserData>::TryStoreConditional(
// old value:
reinterpret_cast<cas_t>(field->Load()),
// linked SCX operations:
&info_fields_[thread_id],
info_fields,
// initial operation state:
OperationState::InProgress);
return scx.Help();
}
template< class UserData >
bool LlxScx<UserData>::TryValidateLink(
template< typename UserData, typename ValuePool >
bool LlxScx<UserData, ValuePool>::TryValidateLink(
const DataRecord_t & field) {
return true; // @TODO
}
// LlxScxRecord
template< class UserData >
template< typename UserData >
LlxScxRecord<UserData>::LlxScxRecord()
: marked_for_finalize_(false) {
scx_op_.Store(&dummy_scx);
}
template< class UserData >
template< typename UserData >
LlxScxRecord<UserData>::LlxScxRecord(
const UserData & user_data)
: user_data_(user_data),
......@@ -293,24 +202,26 @@ LlxScxRecord<UserData>::LlxScxRecord(
// internal::ScxRecord
template< class DataRecord >
template< typename DataRecord >
bool internal::ScxRecord<DataRecord>::Help() {
// We ensure that an SCX S does not change a data record
// while it is frozen for another SCX S'. Instead, S uses
// the information in the SCX record of S' to help S'
// complete, so that the data record can be unfrozen.
typedef embb::containers::internal::FixedSizeList<DataRecord *> dr_list_t;
typedef embb::containers::internal::FixedSizeList<self_t> op_list_t;
// Freeze all data records in data_records to protect their
// mutable fields from being changed by other SCXs:
dr_list_t::iterator linked_it = linked_data_records_->begin();
dr_list_t::iterator linked_end = linked_data_records_->end();
for (unsigned int fieldIdx = 0;
linked_it != linked_end;
++linked_it, ++fieldIdx) {
op_list_t::iterator scx_op_it = scx_ops_->begin();
op_list_t::iterator scx_op_end = scx_ops_->end();
for (; linked_it != linked_end && scx_op_it != scx_op_end;
++linked_it, ++scx_op_it) {
DataRecord * r = *linked_it;
// pointer indexed by r in this->info_fields:
ScxRecord<DataRecord> * rinfo = &info_fields_[fieldIdx];
if (!r->ScxInfo().CompareAndSwap(rinfo, this)) {
ScxRecord<DataRecord> * rinfo_exp = &(*scx_op_it);
if (!r->ScxInfo().CompareAndSwap(rinfo_exp, this)) {
if (r->ScxInfo().Load() != this) {
// could not freeze r because it is frozen for
// another SCX:
......@@ -331,10 +242,8 @@ bool internal::ScxRecord<DataRecord>::Help() {
// mark step:
dr_list_t::iterator finalize_it = finalize_data_records_->begin();
dr_list_t::iterator finalize_end = finalize_data_records_->end();
for (unsigned int field_idx = finalize_range_.first;
finalize_it != finalize_end;
++finalize_it, ++fieldRangeIdx) {
linked_data_records_[fieldRangeIdx]->MarkForFinalize();
for (; finalize_it != finalize_end; ++finalize_it) {
(*finalize_it)->MarkForFinalize();
}
// update CAS:
cas_t expected_old_value = old_value_;
......@@ -347,6 +256,11 @@ bool internal::ScxRecord<DataRecord>::Help() {
return true;
}
template< typename UserData >
internal::ScxRecord< LlxScxRecord<UserData> >
LlxScxRecord<UserData>::dummy_scx =
internal::ScxRecord< LlxScxRecord<UserData> >();
} // namespace primitives
} // namespace containers
} // namespace embb
......
containers_cpp/include/embb/containers/primitives/llx_scx.h
......@@ -30,6 +30,8 @@
#include <embb/base/thread.h>
#include <embb/base/atomic.h>
#include <embb/base/thread_specific_storage.h>
#include <embb/containers/object_pool.h>
#include <embb/containers/lock_free_tree_value_pool.h>
#include <embb/containers/internal/fixed_size_list.h>
namespace embb {
......@@ -42,7 +44,7 @@ namespace internal {
* SCX operation description. An SCX record contains all information
* required to allow any process to complete a pending SCX operation.
*/
template< class DataRecord >
template< typename DataRecord >
class ScxRecord {
private:
......@@ -66,11 +68,11 @@ class ScxRecord {
*/
ScxRecord()
: linked_data_records_(0),
finalize_data_records_(0)
finalize_data_records_(0),
new_value_(0),
old_value_(0),
scx_ops_(0),
state_(OperationState::Undefined),
state_(OperationState::Comitted),
all_frozen_(false) {
field_ = 0;
}
......@@ -84,7 +86,7 @@ class ScxRecord {
embb::base::Atomic<cas_t> * field,
cas_t new_value,
cas_t old_value,
embb::containers::internal::FixedSizeList<self_t *> * scx_ops,
embb::containers::internal::FixedSizeList<self_t> * scx_ops,
OperationState operation_state)
: linked_data_records_(&linked_data_records),
finalize_data_records_(&finalize_data_records),
......@@ -143,7 +145,7 @@ class ScxRecord {
* List of SCX operation descriptions associated with data records
* linked with this SCX operation.
*/
embb::containers::internal::FixedSizeList<self_t *> scx_ops_;
embb::containers::internal::FixedSizeList<self_t> * scx_ops_;
/**
* Current state of this SCX record.
......@@ -165,7 +167,7 @@ class ScxRecord {
* Wraps user-defined data with fields required for LLX/SCX algorithm.
* Mutable fields must each be contained in a single word.
*/
template< class UserData >
template< typename UserData >
class LlxScxRecord {
private:
......@@ -203,9 +205,12 @@ class LlxScxRecord {
* Assignment operator.
*/
LlxScxRecord & operator=(const LlxScxRecord & rhs) {
user_data_ = rhs.user_data_;
scx_op_.Store(rhs.scx_info_.Load());
marked_for_finalize_ = rhs.marked_for_finalize_;
if (this != &rhs) {
user_data_ = rhs.user_data_;
scx_op_.Store(rhs.scx_op_.Load());
marked_for_finalize_ = rhs.marked_for_finalize_;
}
return *this;
}
/**
......@@ -299,10 +304,13 @@ class LlxScxRecord {
* "Pragmatic Primitives for Non-blocking Data Structures"
* (Brown et al., 2013).
*
* \tparam MaxLinks Maximum number of active LL-dependencies per thread
* \tparam UserData Type containing mutable fields
* \tparam ValuePool Type containing mutable fields
*/
template< class UserData >
template<
typename UserData,
typename ValuePool = embb::containers::LockFreeTreeValuePool< bool, false >
>
class LlxScx {
private:
......@@ -335,8 +343,7 @@ class LlxScx {
DataRecord_t * const data_record,
/**< [IN] Pointer to data record to load */
DataRecord_t & data,
/**< [OUT] Atomic snapshot of \c NumMutableFields fields in data
record at given index */
/**< [OUT] Atomic snapshot of data record */
bool & finalized
/**< [OUT] Indicating whether requested fields have been finalized */
);
......@@ -393,6 +400,11 @@ class LlxScx {
size_t max_links_;
/**
* Maximum number of threads engaging in operations on this LLX/SCX instance.
*/
unsigned int max_threads_;
/**
* Shared table containing for each r in V, a copy of r's info
* value in this thread's local table of LLX results.
*
......@@ -402,23 +414,38 @@ class LlxScx {
* r_i in V -> *ScxRecord(thread_llx_results_[r_i].data_record.ScxInfo())
* }
*/
embb::containers::internal::FixedSizeList<ScxRecord_t> * info_fields_;
// embb::containers::internal::FixedSizeList<ScxRecord_t> * info_fields_;
/**
* Shared table containing for each r in V, a copy of r's info
* value in this thread's local table of LLX results.
*
* thread_id -> {
* r_1 in V -> *ScxRecord(thread_llx_results_[r_1].data_record.ScxInfo()),
* ...
* r_i in V -> *ScxRecord(thread_llx_results_[r_i].data_record.ScxInfo())
* }
*/
embb::containers::ObjectPool<
embb::containers::internal::FixedSizeList<ScxRecord_t>, ValuePool >
scx_record_list_pool_;
/**
* Thread-specific list of LLX results performed by the thread.
*/
embb::base::ThreadSpecificStorage<
embb::containers::internal::FixedSizeList<LlxResult> >
thread_llx_results_;
embb::containers::internal::FixedSizeList<LlxResult> *
thread_llx_results_;
/**
* Prevent default construction.
*/
LlxScx();
/**
* Prevent copy construction.
*/
LlxScx(const LlxScx &);
/**
* Prevent assignment.
*/
......
containers_cpp/test/llx_scx_test.cc
......@@ -37,14 +37,13 @@ using embb::containers::primitives::LlxScxRecord;
using embb::containers::primitives::LlxScx;
LlxScxTest::LlxScxTest() :
num_threads_(static_cast<int>
(partest::TestSuite::GetDefaultNumThreads())) {
num_threads_(
static_cast<int>(partest::TestSuite::GetDefaultNumThreads())) {
CreateUnit("SerialTest").Add(&LlxScxTest::SerialTest, this);
}
void LlxScxTest::SerialTest() {
typedef LlxScxTest::Node Node;
// Global:
LlxScx<Node> llxscx(3);
......@@ -72,7 +71,7 @@ void LlxScxTest::SerialTest() {
PT_ASSERT(llxscx.TryLoadLinked(&dr3, l3, finalized));
PT_ASSERT(!finalized);
FixedSizeList< LlxScxRecord<Node> * >
FixedSizeList< LlxScxRecord<Node> * >
linked_deps(3);
linked_deps.PushBack(&dr1);
linked_deps.PushBack(&dr2);
......@@ -92,6 +91,12 @@ void LlxScxTest::SerialTest() {
linked_deps, // V: dependencies, must be LL'd before
finalize_deps // R: Subsequence of V to be finalized
));
// Following LLX calls on finalized data records are
// expected to fail:
PT_ASSERT(!llxscx.TryLoadLinked(&dr2, l2, finalized));
PT_ASSERT(finalized);
PT_ASSERT(!llxscx.TryLoadLinked(&dr3, l3, finalized));
PT_ASSERT(finalized);
}
} // namespace test
......
containers_cpp/test/llx_scx_test.h
......@@ -66,10 +66,19 @@ class LlxScxTest : public partest::TestCase {
next_.Store(next_node);
}
Node(const Node & other)
: value_(other.value_) {
next_.Store(other.next_.Load());
count_.Store(other.count_.Load());
}
Node & operator=(const Node & rhs) {
count_.Store(rhs.count_.Load());
next_.Store(rhs.next_.Load());
value_ = rhs.value_;
if (this != &rhs) {
count_.Store(rhs.count_.Load());
next_.Store(rhs.next_.Load());
value_ = rhs.value_;
}
return *this;
}
};
......
containers_cpp/test/main.cc
......@@ -40,6 +40,7 @@
#include "./stack_test.h"
#include "./hazard_pointer_test.h"
#include "./object_pool_test.h"
#include "./llx_scx_test.h"
#define COMMA ,
......@@ -55,6 +56,7 @@ using embb::containers::test::HazardPointerTest;
using embb::containers::test::QueueTest;
using embb::containers::test::StackTest;
using embb::containers::test::ObjectPoolTest;
using embb::containers::test::LlxScxTest;
PT_MAIN("Data Structures C++") {
unsigned int max_threads = static_cast<unsigned int>(
......@@ -70,6 +72,7 @@ PT_MAIN("Data Structures C++") {
PT_RUN(StackTest< LockFreeStack<int> >);
PT_RUN(ObjectPoolTest< LockFreeTreeValuePool<bool COMMA false > >);
PT_RUN(ObjectPoolTest< WaitFreeArrayValuePool<bool COMMA false> >);
PT_RUN(LlxScxTest);
PT_EXPECT(embb_get_bytes_allocated() == 0);
}
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