From 83ad65f31b5c9441ae1618614082e584854a14e1 Mon Sep 17 00:00:00 2001
From: Gleb Naumenko <naumenko.gs@gmail.com>
Date: Tue, 11 Aug 2020 13:39:56 +0300
Subject: [PATCH] Address nits in ADDR caching

---
 src/net.cpp | 12 ++++++------
 src/net.h   |  8 ++++----
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/net.cpp b/src/net.cpp
index e43b4806123..8ac45dbcb59 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -2550,10 +2550,10 @@ std::vector<CAddress> CConnman::GetAddresses(CNode& requestor, size_t max_addres
         .Write(local_socket_bytes.data(), local_socket_bytes.size())
         .Finalize();
     const auto current_time = GetTime<std::chrono::microseconds>();
-    if (m_addr_response_caches.find(cache_id) == m_addr_response_caches.end() ||
-        m_addr_response_caches[cache_id].m_update_addr_response < current_time) {
-        m_addr_response_caches[cache_id].m_addrs_response_cache = GetAddresses(max_addresses, max_pct);
-
+    auto r = m_addr_response_caches.emplace(cache_id, CachedAddrResponse{});
+    CachedAddrResponse& cache_entry = r.first->second;
+    if (cache_entry.m_cache_entry_expiration < current_time) { // If emplace() added new one it has expiration 0.
+        cache_entry.m_addrs_response_cache = GetAddresses(max_addresses, max_pct);
         // Choosing a proper cache lifetime is a trade-off between the privacy leak minimization
         // and the usefulness of ADDR responses to honest users.
         //
@@ -2578,9 +2578,9 @@ std::vector<CAddress> CConnman::GetAddresses(CNode& requestor, size_t max_addres
         // nodes to be "terrible" (see IsTerrible()) if the timestamps are older than 30 days,
         // max. 24 hours of "penalty" due to cache shouldn't make any meaningful difference
         // in terms of the freshness of the response.
-        m_addr_response_caches[cache_id].m_update_addr_response = current_time + std::chrono::hours(21) + GetRandMillis(std::chrono::hours(6));
+        cache_entry.m_cache_entry_expiration = current_time + std::chrono::hours(21) + GetRandMillis(std::chrono::hours(6));
     }
-    return m_addr_response_caches[cache_id].m_addrs_response_cache;
+    return cache_entry.m_addrs_response_cache;
 }
 
 bool CConnman::AddNode(const std::string& strNode)
diff --git a/src/net.h b/src/net.h
index c9ab579eb24..21faea591ac 100644
--- a/src/net.h
+++ b/src/net.h
@@ -442,7 +442,7 @@ private:
      */
     struct CachedAddrResponse {
         std::vector<CAddress> m_addrs_response_cache;
-        std::chrono::microseconds m_update_addr_response{0};
+        std::chrono::microseconds m_cache_entry_expiration{0};
     };
 
     /**
@@ -454,10 +454,10 @@ private:
      * Indexing by local socket prevents leakage when a node has multiple
      * listening addresses on the same network.
      *
-     * The used memory equals to 1000 CAddress records (or around 32 bytes) per
+     * The used memory equals to 1000 CAddress records (or around 40 bytes) per
      * distinct Network (up to 5) we have/had an inbound peer from,
-     * resulting in at most ~160 KB. Every separate local socket may
-     * add up to ~160 KB extra.
+     * resulting in at most ~196 KB. Every separate local socket may
+     * add up to ~196 KB extra.
      */
     std::map<uint64_t, CachedAddrResponse> m_addr_response_caches;