Merge bitcoin/bitcoin#27745: addrman: select addresses by network follow-up

cd8ef5b3e6 test: ensure addrman test is finite (Amiti Uttarwar)
b9f1e86f12 addrman: change asserts to Assumes (Amiti Uttarwar)
768770771f doc: update `Select` function description (Amiti Uttarwar)
2b6bd12eea refactor: de-duplicate lookups (Amiti Uttarwar)

Pull request description:

  this PR addresses outstanding review comments from #27214

ACKs for top commit:
  achow101:
    ACK cd8ef5b3e6
  mzumsande:
    Code Review ACK cd8ef5b3e6
  brunoerg:
    crACK cd8ef5b3e6

Tree-SHA512: 669f67904263e3f51c39b175eabf5fa1b1e7b6841e889656afec33d0bd93fb446de9403f0a91b186ddeaf29498c8938484a0547b1188256c4e7c90db6f30bb55

src/addrman.cpp

@@ -757,16 +757,14 @@ std::pair<CAddress, NodeSeconds> AddrManImpl::Select_(bool new_only, std::option
 
         // Iterate over the positions of that bucket, starting at the initial one,
         // and looping around.
-        int i;
+        int i, position, node_id;
         for (i = 0; i < ADDRMAN_BUCKET_SIZE; ++i) {
-            int position = (initial_position + i) % ADDRMAN_BUCKET_SIZE;
+            position = (initial_position + i) % ADDRMAN_BUCKET_SIZE;
-            int node_id = GetEntry(search_tried, bucket, position);
+            node_id = GetEntry(search_tried, bucket, position);
             if (node_id != -1) {
                 if (network.has_value()) {
                     const auto it{mapInfo.find(node_id)};
-                    assert(it != mapInfo.end());
+                    if (Assume(it != mapInfo.end()) && it->second.GetNetwork() == *network) break;
-                    const auto info{it->second};
-                    if (info.GetNetwork() == *network) break;
                 } else {
                     break;
                 }
@@ -777,9 +775,7 @@ std::pair<CAddress, NodeSeconds> AddrManImpl::Select_(bool new_only, std::option
         if (i == ADDRMAN_BUCKET_SIZE) continue;
 
         // Find the entry to return.
-        int position = (initial_position + i) % ADDRMAN_BUCKET_SIZE;
+        const auto it_found{mapInfo.find(node_id)};
-        int nId = GetEntry(search_tried, bucket, position);
-        const auto it_found{mapInfo.find(nId)};
         assert(it_found != mapInfo.end());
         const AddrInfo& info{it_found->second};
 
@@ -798,17 +794,19 @@ int AddrManImpl::GetEntry(bool use_tried, size_t bucket, size_t position) const
 {
     AssertLockHeld(cs);
 
-    assert(position < ADDRMAN_BUCKET_SIZE);
-
     if (use_tried) {
-        assert(bucket < ADDRMAN_TRIED_BUCKET_COUNT);
+        if (Assume(position < ADDRMAN_BUCKET_SIZE) && Assume(bucket < ADDRMAN_TRIED_BUCKET_COUNT)) {
             return vvTried[bucket][position];
+        }
     } else {
-        assert(bucket < ADDRMAN_NEW_BUCKET_COUNT);
+        if (Assume(position < ADDRMAN_BUCKET_SIZE) && Assume(bucket < ADDRMAN_NEW_BUCKET_COUNT)) {
             return vvNew[bucket][position];
         }
     }
 
+    return -1;
+}
+
 std::vector<CAddress> AddrManImpl::GetAddr_(size_t max_addresses, size_t max_pct, std::optional<Network> network) const
 {
     AssertLockHeld(cs);

src/addrman.h

@@ -148,8 +148,10 @@ public:
      *
      * @param[in] new_only Whether to only select addresses from the new table. Passing `true` returns
      *                     an address from the new table or an empty pair. Passing `false` will return an
-     *                     address from either the new or tried table (it does not guarantee a tried entry).
+     *                     empty pair or an address from either the new or tried table (it does not
-     * @param[in] network  Select only addresses of this network (nullopt = all)
+     *                     guarantee a tried entry).
+     * @param[in] network  Select only addresses of this network (nullopt = all). Passing a network may
+     *                     slow down the search.
      * @return    CAddress The record for the selected peer.
      *            seconds  The last time we attempted to connect to that peer.
      */

src/addrman_impl.h

@@ -255,7 +255,7 @@ private:
 
     /** Helper to generalize looking up an addrman entry from either table.
      *
-     *  @return  int The nid of the entry or -1 if the addrman position is empty.
+     *  @return  int The nid of the entry. If the addrman position is empty or not found, returns -1.
      * */
     int GetEntry(bool use_tried, size_t bucket, size_t position) const EXCLUSIVE_LOCKS_REQUIRED(cs);
 

src/test/addrman_tests.cpp

@@ -239,8 +239,9 @@ BOOST_AUTO_TEST_CASE(addrman_select_by_network)
     // ensure that both new and tried table are selected from
     bool new_selected{false};
     bool tried_selected{false};
+    int counter = 256;
 
-    while (!new_selected || !tried_selected) {
+    while (--counter > 0 && (!new_selected || !tried_selected)) {
         const CAddress selected{addrman->Select(/*new_only=*/false, NET_I2P).first};
         BOOST_REQUIRE(selected == i2p_addr || selected == i2p_addr2);
         if (selected == i2p_addr) {
@@ -249,6 +250,9 @@ BOOST_AUTO_TEST_CASE(addrman_select_by_network)
             new_selected = true;
         }
     }
+
+    BOOST_CHECK(new_selected);
+    BOOST_CHECK(tried_selected);
 }
 
 BOOST_AUTO_TEST_CASE(addrman_select_special)