From 7b964eb9d6b8f971cfe727e483f3b9cac82b9c61 Mon Sep 17 00:00:00 2001
From: Recolic K <bensl@microsoft.com>
Date: Tue, 17 May 2022 18:38:25 +0800
Subject: [PATCH] msgbuf
---
src/lib/msgbuf.hpp | 70 ++++++++++++++++++----------------------------
1 file changed, 27 insertions(+), 43 deletions(-)
diff --git a/src/lib/msgbuf.hpp b/src/lib/msgbuf.hpp
index 898eaaf..ce531ed 100644
--- a/src/lib/msgbuf.hpp
+++ b/src/lib/msgbuf.hpp
@@ -7,6 +7,8 @@
#include <atomic>
#include <memory>
#include <stdexcept>
+#include <rlib/stdio.hpp>
+
using std::size_t;
namespace rlib {
@@ -16,29 +18,34 @@ namespace rlib {
struct node {
std::atomic<node *> next;
ElementType *payload;
- explicit node(ElementType *payload) : payload(payload), next(nullptr) {}
+ explicit node(ElementType *payload, bool nonnull = true) : payload(payload), next(nullptr) {
+ if(nonnull)
+ assert(payload != nullptr);
+ }
};
using apnode_t = std::atomic<node *>;
// push to back (tail), pop from front (head).
// To make it simple, the head node always exists. So pop will not hurt tail, and push will not change head.
apnode_t head, tail;
- static constexpr node *NULLPTR = nullptr;
// List structure is the primary concern, we must keep the list structure consistent before taking care of head/tail ptr.
void do_push_back(node *new_ele) {
+ node *NULLPTR = nullptr;
auto tail_node_ptr = tail.load();
while(!std::atomic_compare_exchange_weak(&tail_node_ptr->next, &NULLPTR, new_ele)) {
// If failed to link the node to the tail, we catch up and try again.
+ NULLPTR = nullptr;
tail_node_ptr = tail.load();
}
// Move the tail ptr. If we succeed, that's good. (I don't think we might fail here)
- // TODO: prove that we will not fail here.
- std::atomic_compare_exchange_strong(&tail, tail_node_ptr, new_ele);
+ // TODO: prove that we will not fail here. Note: push-push scenario, we are safe.
+ auto res = std::atomic_compare_exchange_strong(&tail, &tail_node_ptr, new_ele);
+ assert(res);
}
- node *do_pop_front() {
+ ElementType *do_pop_front() {
node *head_node_ptr;
do {
head_node_ptr = head.load();
@@ -46,59 +53,36 @@ namespace rlib {
return nullptr;
// We move the head pointer forward to pop. (It will never invalidate tail node)
// If failed, just try again.
- } while(!std::atomic_compare_exchange_weak(&head, head_node_ptr, head_node_ptr->next));
+ } while(!std::atomic_compare_exchange_weak(&head, &head_node_ptr, head_node_ptr->next));
// I love this idea: value stored in head->next->data, instead of head->data.
- std::swap(head_node_ptr->payload = head_node_ptr->next->payload);
- return head_node_ptr;
- // TODO: Warning: the returned pointer is not safe to delete!
+ auto payload_to_return = head_node_ptr->next.load()->payload;
+ head_node_ptr->next.load()->payload = nullptr;
+
+ assert(payload_to_return != nullptr);
+ assert(*payload_to_return == 1);
+ return payload_to_return;
+
+ // TODO: delete head_node_ptr
}
public:
thread_safe_queue()
- : head(new node(nullptr)), tail(head) {}
+ : head(new node(nullptr, false)), tail(head.load()) {}
+ void push(const ElementType &payload) {
+ do_push_back(new node(new ElementType(payload)));
+ }
void push(ElementType &&payload) {
do_push_back(new node(new ElementType(std::forward<ElementType>(payload))));
}
- std::shared_ptr<ElementType> pop() {
+ auto pop() {
auto ret = do_pop_front();
if(ret)
- return std::make_shared(ret->payload);
+ return std::shared_ptr<ElementType>(ret);
else
throw std::out_of_range("pop empty queue");
}
};
}
-
- // This buffer is intended to buffer messages in different threads.
- class dgram_msgbuf {
- // This option is used for debugging. If the data structure is buggy, turn this on and see if it's good.
- static constexpr auto ENABLE_LOCK = false;
-
- struct dgram_t {
- uint32_t length;
- char *dataptr;
- };
-
- public:
- dgram_msgbuf(size_t buffer_size, size_t max_grams) {
- assert(! (buffer_size & 0xffffffff00000000ull));
- buffer = (char *)std::malloc(buffer_size);
- grams = new subset_t[max_grams];
- }
- ~dgram_msgbuf() {
- std::free(buffer);
- delete[] grams;
- }
-
- char *new_element(size_t bytes) {
- // Create a new entry,
-
- }
-
- private:
- char *buffer = nullptr;
- subset_t *grams = nullptr;
- };
}
#endif
--
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