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Fix concurrent query module race condition (#1158)

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Concurrent access to the same query module had a race condition on the
pointer that was used to handle the custom memory management. With this
commit, a mapping has been added to keep information about what
thread used the pointer to handle the memory resources. This should be
fine since the respected query executions are running on a dedicated
thread. Access to the mapping itself is threadsafe. A simple RAII
wrapper for the mapping container has also been added for simpler
client-side use.
This commit is contained in:
gvolfing
2023-08-21 16:45:36 +02:00
committed by GitHub
parent 97183fb9da
commit 476968e2c8
11 changed files with 427 additions and 159 deletions
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38
query_modules/example.cpp
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@@ -1,4 +1,4 @@
// Copyright 2022 Memgraph Ltd.
// Copyright 2023 Memgraph Ltd.
//
// Use of this software is governed by the Business Source License
// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
@@ -18,7 +18,11 @@ void ProcImpl(std::vector<mgp::Value> arguments, mgp::Graph graph, mgp::RecordFa
void SampleReadProc(mgp_list *args, mgp_graph *memgraph_graph, mgp_result *result, mgp_memory *memory) {
try {
mgp::memory = memory;
// The outcommented way of assigning the memory pointer is still
// working, but it is deprecated because of certain concurrency
// issues. Please use the guard instead.
// mgp::memory = memory;
mgp::MemoryDispatcherGuard guard(memory);
std::vector<mgp::Value> arguments;
for (size_t i = 0; i < mgp::list_size(args); i++) {
@@ -34,7 +38,11 @@ void SampleReadProc(mgp_list *args, mgp_graph *memgraph_graph, mgp_result *resul
}
void AddXNodes(mgp_list *args, mgp_graph *memgraph_graph, mgp_result *result, mgp_memory *memory) {
mgp::memory = memory;
// The outcommented way of assigning the memory pointer is still
// working, but it is deprecated because of certain concurrency
// issues. Please use the guard instead.
// mgp::memory = memory;
mgp::MemoryDispatcherGuard guard(memory);
auto graph = mgp::Graph(memgraph_graph);
std::vector<mgp::Value> arguments;
@@ -49,7 +57,11 @@ void AddXNodes(mgp_list *args, mgp_graph *memgraph_graph, mgp_result *result, mg
}
void Multiply(mgp_list *args, mgp_func_context *ctx, mgp_func_result *res, mgp_memory *memory) {
mgp::memory = memory;
// The outcommented way of assigning the memory pointer is still
// working, but it is deprecated because of certain concurrency
// issues. Please use the guard instead.
// mgp::memory = memory;
mgp::MemoryDispatcherGuard guard(memory);
std::vector<mgp::Value> arguments;
for (size_t i = 0; i < mgp::list_size(args); i++) {
@@ -67,7 +79,11 @@ void Multiply(mgp_list *args, mgp_func_context *ctx, mgp_func_result *res, mgp_m
extern "C" int mgp_init_module(struct mgp_module *module, struct mgp_memory *memory) {
try {
mgp::memory = memory;
// The outcommented way of assigning the memory pointer is still
// working, but it is deprecated because of certain concurrency
// issues. Please use the guard instead.
// mgp::memory = memory;
mgp::MemoryDispatcherGuard guard(memory);
AddProcedure(SampleReadProc, "return_true", mgp::ProcedureType::Read,
{mgp::Parameter("param_1", mgp::Type::Int), mgp::Parameter("param_2", mgp::Type::Double, 2.3)},
@@ -77,7 +93,11 @@ extern "C" int mgp_init_module(struct mgp_module *module, struct mgp_memory *mem
}
try {
mgp::memory = memory;
// The outcommented way of assigning the memory pointer is still
// working, but it is deprecated because of certain concurrency
// issues. Please use the guard instead.
// mgp::memory = memory;
mgp::MemoryDispatcherGuard guard(memory);
mgp::AddProcedure(AddXNodes, "add_x_nodes", mgp::ProcedureType::Write, {mgp::Parameter("param_1", mgp::Type::Int)},
{}, module, memory);
@@ -87,7 +107,11 @@ extern "C" int mgp_init_module(struct mgp_module *module, struct mgp_memory *mem
}
try {
mgp::memory = memory;
// The outcommented way of assigning the memory pointer is still
// working, but it is deprecated because of certain concurrency
// issues. Please use the guard instead.
// mgp::memory = memory;
mgp::MemoryDispatcherGuard guard(memory);
mgp::AddFunction(Multiply, "multiply",
{mgp::Parameter("int", mgp::Type::Int), mgp::Parameter("int", mgp::Type::Int, (int64_t)3)}, module,