Incremental improvements to path finding memory usage:

* Abort background path finding when closed or disconnected
* Exit pathfinding job thread if there are no requests left
* Don't bother creating the path find job if there are no requests
* Refactor to remove circular dependency between InfoSub and PathRequest

src/test/basics/join_test.cpp

@@ -0,0 +1,105 @@
+//------------------------------------------------------------------------------
+/*
+This file is part of rippled: https://github.com/ripple/rippled
+Copyright (c) 2022 Ripple Labs Inc.
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose  with  or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <test/jtx/Account.h>
+
+#include <ripple/basics/join.h>
+#include <ripple/beast/unit_test.h>
+
+namespace ripple {
+namespace test {
+
+struct join_test : beast::unit_test::suite
+{
+    void
+    run() override
+    {
+        auto test = [this](auto collectionanddelimiter, std::string expected) {
+            std::stringstream ss;
+            // Put something else in the buffer before and after to ensure that
+            // the << operator returns the stream correctly.
+            ss << "(" << collectionanddelimiter << ")";
+            auto const str = ss.str();
+            BEAST_EXPECT(str.substr(1, str.length() - 2) == expected);
+            BEAST_EXPECT(str.front() == '(');
+            BEAST_EXPECT(str.back() == ')');
+        };
+
+        // C++ array
+        test(
+            CollectionAndDelimiter(std::array<int, 4>{2, -1, 5, 10}, "/"),
+            "2/-1/5/10");
+        // One item C++ array edge case
+        test(
+            CollectionAndDelimiter(std::array<std::string, 1>{"test"}, " & "),
+            "test");
+        // Empty C++ array edge case
+        test(CollectionAndDelimiter(std::array<int, 0>{}, ","), "");
+        {
+            // C-style array
+            char letters[4]{'w', 'a', 's', 'd'};
+            test(CollectionAndDelimiter(letters, std::to_string(0)), "w0a0s0d");
+        }
+        {
+            // Auto sized C-style array
+            std::string words[]{"one", "two", "three", "four"};
+            test(CollectionAndDelimiter(words, "\n"), "one\ntwo\nthree\nfour");
+        }
+        {
+            // One item C-style array edge case
+            std::string words[]{"thing"};
+            test(CollectionAndDelimiter(words, "\n"), "thing");
+        }
+        // Initializer list
+        test(
+            CollectionAndDelimiter(std::initializer_list<size_t>{19, 25}, "+"),
+            "19+25");
+        // vector
+        test(
+            CollectionAndDelimiter(std::vector<int>{0, 42}, std::to_string(99)),
+            "09942");
+        {
+            // vector with one item edge case
+            using namespace jtx;
+            test(
+                CollectionAndDelimiter(
+                    std::vector<Account>{Account::master}, "xxx"),
+                Account::master.human());
+        }
+        // empty vector edge case
+        test(CollectionAndDelimiter(std::vector<uint256>{}, ","), "");
+        // C-style string
+        test(CollectionAndDelimiter("string", " "), "s t r i n g");
+        // Empty C-style string edge case
+        test(CollectionAndDelimiter("", "*"), "");
+        // Single char C-style string edge case
+        test(CollectionAndDelimiter("x", "*"), "x");
+        // std::string
+        test(CollectionAndDelimiter(std::string{"string"}, "-"), "s-t-r-i-n-g");
+        // Empty std::string edge case
+        test(CollectionAndDelimiter(std::string{""}, "*"), "");
+        // Single char std::string edge case
+        test(CollectionAndDelimiter(std::string{"y"}, "*"), "y");
+    }
+};  // namespace test
+
+BEAST_DEFINE_TESTSUITE(join, ripple_basics, ripple);
+
+}  // namespace test
+}  // namespace ripple