From 7fd50c3b70397c0dc39093a7a4ddbf9b36a615cf Mon Sep 17 00:00:00 2001
From: John Newbery <john@johnnewbery.com>
Date: Mon, 10 Apr 2017 10:34:23 -0400
Subject: [PATCH] allow libevent logging to be updated during runtime

---
 src/Makefile.test.include |  2 +-
 src/rpc/misc.cpp          | 15 +++++++++++++++
 src/util.cpp              |  2 +-
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index fe0ed59fe..d08c8bde5 100644
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -97,7 +97,7 @@ endif
 test_test_bitcoin_SOURCES = $(BITCOIN_TESTS) $(JSON_TEST_FILES) $(RAW_TEST_FILES)
 test_test_bitcoin_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) -I$(builddir)/test/ $(TESTDEFS) $(EVENT_CFLAGS)
 test_test_bitcoin_LDADD = $(LIBBITCOIN_SERVER) $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBUNIVALUE) $(LIBLEVELDB) $(LIBMEMENV) \
-  $(BOOST_LIBS) $(BOOST_UNIT_TEST_FRAMEWORK_LIB) $(LIBSECP256K1) $(EVENT_LIBS)
+  $(BOOST_LIBS) $(BOOST_UNIT_TEST_FRAMEWORK_LIB) $(LIBSECP256K1) $(EVENT_LIBS) $(EVENT_PTHREADS_LIBS)
 test_test_bitcoin_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 if ENABLE_WALLET
 test_test_bitcoin_LDADD += $(LIBBITCOIN_WALLET)
diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index d20184771..7b8aa572d 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -7,6 +7,7 @@
 #include "clientversion.h"
 #include "init.h"
 #include "validation.h"
+#include "httpserver.h"
 #include "net.h"
 #include "netbase.h"
 #include "rpc/blockchain.h"
@@ -598,6 +599,20 @@ UniValue logging(const JSONRPCRequest& request)
         logCategories &= ~getCategoryMask(request.params[1]);
     }
 
+    // Update libevent logging if BCLog::LIBEVENT has changed.
+    // If the library version doesn't allow it, UpdateHTTPServerLogging() returns false,
+    // in which case we should clear the BCLog::LIBEVENT flag.
+    // Throw an error if the user has explicitly asked to change only the libevent
+    // flag and it failed.
+    uint32_t changedLogCategories = originalLogCategories ^ logCategories;
+    if (changedLogCategories & BCLog::LIBEVENT) {
+        if (!UpdateHTTPServerLogging(logCategories & BCLog::LIBEVENT)) {
+            logCategories &= ~BCLog::LIBEVENT;
+            if (changedLogCategories == BCLog::LIBEVENT) {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "libevent logging cannot be updated when using libevent before v2.1.1.");
+            }
+        }
+    }
 
     UniValue result(UniValue::VOBJ);
     std::vector<CLogCategoryActive> vLogCatActive = ListActiveLogCategories();
diff --git a/src/util.cpp b/src/util.cpp
index e859c8a1a..0dc203cba 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -118,7 +118,7 @@ bool fLogIPs = DEFAULT_LOGIPS;
 std::atomic<bool> fReopenDebugLog(false);
 CTranslationInterface translationInterface;
 
-/** Log categories bitfield. libevent needs special handling if their flags are changed at runtime. */
+/** Log categories bitfield. */
 std::atomic<uint32_t> logCategories(0);
 
 /** Init OpenSSL library multithreading support */