Merge bitcoin/bitcoin#24681: build: Bump libevent minimum version up to 2.1.8

e40779a refactor: Remove outdated libevent logging code (Fabian Jahr)
0598f36 refactor: account for requiring libevent 2.1.8+ (fanquake)
aaf72d6 build: Bump libevent minimum version up to 2.1.8 (Hennadii Stepanov)

Pull request description:

  Required to support new functionality in bitcoin/bitcoin#19420.

  `libevent` availability: https://repology.org/project/libevent/versions

ACKs for top commit:
  laanwj:
    Code review ACK e40779a
  fanquake:
    ACK e40779a

Tree-SHA512: ccb14ea2f591484a3df5bc4a19f4f5400ef6b1cfb7dc45dd99f96cb948748215ed3b5debc34869763c91b8c7a26993fdb9b870950c0743c4d01038ab27c5e4e2

Author: fanquake

configure.ac

@@ -1537,9 +1537,9 @@ fi
 dnl libevent check
 
 if test "$build_bitcoin_cli$build_bitcoind$bitcoin_enable_qt$use_tests$use_bench" != "nonononono"; then
-  PKG_CHECK_MODULES([EVENT], [libevent >= 2.0.21], [use_libevent=yes], [AC_MSG_ERROR([libevent version 2.0.21 or greater not found.])])
+  PKG_CHECK_MODULES([EVENT], [libevent >= 2.1.8], [use_libevent=yes], [AC_MSG_ERROR([libevent version 2.1.8 or greater not found.])])
   if test "$TARGET_OS" != "windows"; then
-    PKG_CHECK_MODULES([EVENT_PTHREADS], [libevent_pthreads >= 2.0.21],, [AC_MSG_ERROR([libevent_pthreads version 2.0.21 or greater not found.])])
+    PKG_CHECK_MODULES([EVENT_PTHREADS], [libevent_pthreads >= 2.1.8], [], [AC_MSG_ERROR([libevent_pthreads version 2.1.8 or greater not found.])])
   fi
 
   if test "$suppress_external_warnings" != "no"; then

doc/dependencies.md

@@ -18,7 +18,7 @@ You can find installation instructions in the `build-*.md` file for your platfor
 | Dependency | Version used | Minimum required | Runtime |
 | --- | --- | --- | --- |
 | [Boost](https://www.boost.org/users/download/) | 1.77.0 | [1.64.0](https://github.com/bitcoin/bitcoin/pull/22320) | No |
-| [libevent](https://github.com/libevent/libevent/releases) | 2.1.12-stable | [2.0.21](https://github.com/bitcoin/bitcoin/pull/18676) | No |
+| [libevent](https://github.com/libevent/libevent/releases) | 2.1.12-stable | [2.1.8](https://github.com/bitcoin/bitcoin/pull/24681) | No |
 | [glibc](https://www.gnu.org/software/libc/) | N/A | [2.18](https://github.com/bitcoin/bitcoin/pull/23511) | Yes |
 
 ## Optional

src/bitcoin-cli.cpp

@@ -184,7 +184,6 @@ struct HTTPReply
 static std::string http_errorstring(int code)
 {
     switch(code) {
-#if LIBEVENT_VERSION_NUMBER >= 0x02010300
     case EVREQ_HTTP_TIMEOUT:
         return "timeout reached";
     case EVREQ_HTTP_EOF:
@@ -197,7 +196,6 @@ static std::string http_errorstring(int code)
         return "request was canceled";
     case EVREQ_HTTP_DATA_TOO_LONG:
         return "response body is larger than allowed";
-#endif
     default:
         return "unknown";
     }
@@ -228,13 +226,11 @@ static void http_request_done(struct evhttp_request *req, void *ctx)
     }
 }
 
-#if LIBEVENT_VERSION_NUMBER >= 0x02010300
 static void http_error_cb(enum evhttp_request_error err, void *ctx)
 {
     HTTPReply *reply = static_cast<HTTPReply*>(ctx);
     reply->error = err;
 }
-#endif
 
 /** Class that handles the conversion from a command-line to a JSON-RPC request,
  * as well as converting back to a JSON object that can be shown as result.
@@ -745,11 +741,11 @@ static UniValue CallRPC(BaseRequestHandler* rh, const std::string& strMethod, co
 
     HTTPReply response;
     raii_evhttp_request req = obtain_evhttp_request(http_request_done, (void*)&response);
-    if (req == nullptr)
+    if (req == nullptr) {
         throw std::runtime_error("create http request failed");
-#if LIBEVENT_VERSION_NUMBER >= 0x02010300
+    }
+
     evhttp_request_set_error_cb(req.get(), http_error_cb);
-#endif
 
     // Get credentials
     std::string strRPCUserColonPass;

src/httpserver.cpp

@@ -360,12 +360,8 @@ bool InitHTTPServer()
 
     // Redirect libevent's logging to our own log
     event_set_log_callback(&libevent_log_cb);
-    // Update libevent's log handling. Returns false if our version of
-    // libevent doesn't support debug logging, in which case we should
-    // clear the BCLog::LIBEVENT flag.
-    if (!UpdateHTTPServerLogging(LogInstance().WillLogCategory(BCLog::LIBEVENT))) {
-        LogInstance().DisableCategory(BCLog::LIBEVENT);
-    }
+    // Update libevent's log handling.
+    UpdateHTTPServerLogging(LogInstance().WillLogCategory(BCLog::LIBEVENT));
 
 #ifdef WIN32
     evthread_use_windows_threads();
@@ -404,18 +400,12 @@ bool InitHTTPServer()
     return true;
 }
 
-bool UpdateHTTPServerLogging(bool enable) {
-#if LIBEVENT_VERSION_NUMBER >= 0x02010100
+void UpdateHTTPServerLogging(bool enable) {
     if (enable) {
         event_enable_debug_logging(EVENT_DBG_ALL);
     } else {
         event_enable_debug_logging(EVENT_DBG_NONE);
     }
-    return true;
-#else
-    // Can't update libevent logging if version < 02010100
-    return false;
-#endif
 }
 
 static std::thread g_thread_http;

src/httpserver.h

@@ -32,9 +32,8 @@ void InterruptHTTPServer();
 /** Stop HTTP server */
 void StopHTTPServer();
 
-/** Change logging level for libevent. Removes BCLog::LIBEVENT from log categories if
- * libevent doesn't support debug logging.*/
-bool UpdateHTTPServerLogging(bool enable);
+/** Change logging level for libevent. */
+void UpdateHTTPServerLogging(bool enable);
 
 /** Handler for requests to a certain HTTP path */
 typedef std::function<bool(HTTPRequest* req, const std::string &)> HTTPRequestHandler;

src/rpc/misc.cpp

@@ -646,17 +646,8 @@ static RPCHelpMan logging()
     uint32_t changed_log_categories = original_log_categories ^ updated_log_categories;
 
     // 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.
     if (changed_log_categories & BCLog::LIBEVENT) {
-        if (!UpdateHTTPServerLogging(LogInstance().WillLogCategory(BCLog::LIBEVENT))) {
-            LogInstance().DisableCategory(BCLog::LIBEVENT);
-            if (changed_log_categories == BCLog::LIBEVENT) {
-            throw JSONRPCError(RPC_INVALID_PARAMETER, "libevent logging cannot be updated when using libevent before v2.1.1.");
-            }
-        }
+        UpdateHTTPServerLogging(LogInstance().WillLogCategory(BCLog::LIBEVENT));
     }
 
     UniValue result(UniValue::VOBJ);

src/test/fuzz/http_request.cpp

@@ -19,23 +19,8 @@
 #include <string>
 #include <vector>
 
-// workaround for libevent versions before 2.1.1,
-// when internal functions didn't have underscores at the end
-#if LIBEVENT_VERSION_NUMBER < 0x02010100
-extern "C" int evhttp_parse_firstline(struct evhttp_request*, struct evbuffer*);
-extern "C" int evhttp_parse_headers(struct evhttp_request*, struct evbuffer*);
-inline int evhttp_parse_firstline_(struct evhttp_request* r, struct evbuffer* b)
-{
-    return evhttp_parse_firstline(r, b);
-}
-inline int evhttp_parse_headers_(struct evhttp_request* r, struct evbuffer* b)
-{
-    return evhttp_parse_headers(r, b);
-}
-#else
 extern "C" int evhttp_parse_firstline_(struct evhttp_request*, struct evbuffer*);
 extern "C" int evhttp_parse_headers_(struct evhttp_request*, struct evbuffer*);
-#endif
 
 std::string RequestMethodString(HTTPRequest::RequestMethod m);