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Vasil Dimov 2025-04-29 11:52:05 +02:00 committed by GitHub
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@ -1002,7 +1002,11 @@ private:
};
/**
* Interface for message handling
* Interface for message handling.
* For a given `CNode`, the methods must be called in the following order:
* 1. `InitializeNode()`
* 2. Any number of calls to `ProcessMessages()` or `SendMessages()`
* 3. `FinalizeNode()`
*/
class NetEventsInterface
{
@ -1010,10 +1014,19 @@ public:
/** Mutex for anything that is only accessed via the msg processing thread */
static Mutex g_msgproc_mutex;
/** Initialize a peer (setup state) */
/**
* Initialize a peer (setup state). The caller is responsible for eventually
* calling `FinalizeNode()` on this node to avoid memory leaks.
* @param[in] node Peer to initialize.
* @param[in] our_services The services that we have advertised to the peer.
*/
virtual void InitializeNode(const CNode& node, ServiceFlags our_services) = 0;
/** Handle removal of a peer (clear state) */
/**
* Handle removal of a peer (clear state).
* When this is called all socket operations with the node must have completed.
* @param[in] node Peer whose state to clear.
*/
virtual void FinalizeNode(const CNode& node) = 0;
/**
@ -1023,23 +1036,26 @@ public:
virtual bool HasAllDesirableServiceFlags(ServiceFlags services) const = 0;
/**
* Process protocol messages received from a given node
*
* @param[in] pnode The node which we have received messages from.
* @param[in] interrupt Interrupt condition for processing threads
* @return True if there is more work to be done
*/
* Process protocol messages received from a given node.
* The caller must make sure that `pnode` is not destroyed and `FinalizeNode()`
* is not called on it during the execution of this function.
*
* @param[in] pnode The node which we have received messages from.
* @param[in] interrupt Interrupt condition for processing threads
* @return True if there is more work to be done
*/
virtual bool ProcessMessages(CNode* pnode, std::atomic<bool>& interrupt) EXCLUSIVE_LOCKS_REQUIRED(g_msgproc_mutex) = 0;
/**
* Send queued protocol messages to a given node.
*
* @param[in] pnode The node which we are sending messages to.
* @return True if there is more work to be done
*/
* Send queued protocol messages to a given node.
* The caller must make sure that `pnode` is not destroyed and `FinalizeNode()`
* is not called on it during the execution of this function.
*
* @param[in] pnode The node which we are sending messages to.
* @return True if there is more work to be done
*/
virtual bool SendMessages(CNode* pnode) EXCLUSIVE_LOCKS_REQUIRED(g_msgproc_mutex) = 0;
protected:
/**
* Protected destructor so that instances can only be deleted by derived classes.
@ -1442,9 +1458,34 @@ private:
std::vector<AddedNodeParams> m_added_node_params GUARDED_BY(m_added_nodes_mutex);
mutable Mutex m_added_nodes_mutex;
/**
* List of peers we are connected with.
* Before destroying objects from this list it must be ensured that
* all socket operations have completed. `m_msgproc` must be informed
* that the node is about to be destroyed by calling `m_msgproc->FinalizeNode()`.
* `m_msgproc->ProcessMessages()` and `m_msgproc->SendMessages()` must not be
* running on that node during the destruction.
*
* CNode objects keep a reference count that is used to avoid a destruction
* while the object is used. All users of elements from `m_nodes` must either
* do so while holding `m_nodes_mutex` or by incrementing the reference before
* use and decrement it after use. To make sure that a new reference is not added
* to a no-referenced CNode just before it is destroyed we use the following
* mechanism (without a help from the standard library):
* - New references are only allowed to be added to objects in `m_nodes`.
* - When an object from `m_nodes` is to be destroyed it is moved from
* `m_nodes` to `m_nodes_disconnected`. Adding new references to objects
* in `m_nodes_disconnected` is not allowed.
* - Once an object in `m_nodes_disconnected` is not referenced anymore,
* then it is safe to destroy it.
*
* So CNode destruction is: wait for no-references, `FinalizeNode()`, delete CNode.
*/
std::vector<CNode*> m_nodes GUARDED_BY(m_nodes_mutex);
std::list<CNode*> m_nodes_disconnected;
mutable RecursiveMutex m_nodes_mutex;
std::list<CNode*> m_nodes_disconnected;
std::atomic<NodeId> nLastNodeId{0};
unsigned int nPrevNodeCount{0};