Merge #19809: log: Prefix log messages with function name and source code location if -logsourcelocations is set

b4511e2e2ed1a6077ae6826a9ee6b7a311293d08 log: Prefix log messages with function name if -logsourcelocations is set (practicalswift)

Pull request description:

  Prefix log messages with function name if `-logfunctionnames` is set.

  Yes, exactly like `-logthreadnames` but for function names instead of thread names :)

  This is a small developer ergonomics improvement: I've found this to be a cheap/simple way to correlate log output and originating function.

  For me it beats the ordinary cycle of 1.) try to figure out a regexp matching the static part of the dynamic log message, 2.) `git grep -E 'Using .* MiB out of .* requested for signature cache'`, 3.) `mcedit filename.cpp` (`openemacs filename.cpp` works too!) and 4.) search for log message and scroll up to find the function name :)

  Without any logging parameters:

  ```
  $ src/bitcoind -regtest
  2020-08-25T03:29:04Z Using RdRand as an additional entropy source
  2020-08-25T03:29:04Z Using 16 MiB out of 32/2 requested for signature cache, able to store 524288 elements
  2020-08-25T03:29:04Z Using 16 MiB out of 32/2 requested for script execution cache, able to store 524288 elements
  2020-08-25T03:29:04Z Loaded best chain: hashBestChain=0fff88f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e22ff height=0 date=2011-02-02T23:16:42Z progress=1.000000
  2020-08-25T03:29:04Z block tree size = 1
  2020-08-25T03:29:04Z nBestHeight = 0
  2020-08-25T03:29:04Z Imported mempool transactions from disk: 0 succeeded, 0 failed, 0 expired, 0 already there, 0 waiting for initial broadcast
  2020-08-25T03:29:04Z 0 addresses found from DNS seeds
  ```

  With `-logthreadnames` and `-logfunctionnames`:

  ```
  $ src/bitcoind -regtest -logthreadnames -logfunctionnames
  2020-08-25T03:29:04Z [init] [ReportHardwareRand] Using RdRand as an additional entropy source
  2020-08-25T03:29:04Z [init] [InitSignatureCache] Using 16 MiB out of 32/2 requested for signature cache, able to store 524288 elements
  2020-08-25T03:29:04Z [init] [InitScriptExecutionCache] Using 16 MiB out of 32/2 requested for script execution cache, able to store 524288 elements
  2020-08-25T03:29:04Z [init] [LoadChainTip] Loaded best chain: hashBestChain=0fff88f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e22ff height=0 date=2011-02-02T23:16:42Z progress=1.000000
  2020-08-25T03:29:04Z [init] [AppInitMain] block tree size = 1
  2020-08-25T03:29:04Z [init] [AppInitMain] nBestHeight = 0
  2020-08-25T03:29:04Z [loadblk] [LoadMempool] Imported mempool transactions from disk: 0 succeeded, 0 failed, 0 expired, 0 already there, 0 waiting for initial broadcast
  2020-08-25T03:29:04Z [dnsseed] [ThreadDNSAddressSeed] 0 addresses found from DNS seeds
  ```

ACKs for top commit:
  laanwj:
    Code review ACK b4511e2e2ed1a6077ae6826a9ee6b7a311293d08
  MarcoFalke:
    review ACK b4511e2e2ed1a6077ae6826a9ee6b7a311293d08 🌃

Tree-SHA512: d100f5364630c323f31d275259864c597f7725e462d5f4bdedcc7033ea616d7fc0d16ef1b2af557e692f4deea73c6773ccfc681589e7bf6ba970b9ec169040c7

3 files changed, 15 insertions, 0 deletions

diff --git a/src/test/fuzz/string.cpp b/src/test/fuzz/string.cpp
index d6bbb17f63..ec8a3b23db 100644
--- a/src/test/fuzz/string.cpp
+++ b/src/test/fuzz/string.cpp
@@ -67,6 +67,7 @@ FUZZ_TARGET(string)
     }
     OutputType output_type;
     (void)ParseOutputType(random_string_1, output_type);
+    (void)RemovePrefix(random_string_1, random_string_2);
     (void)ResolveErrMsg(random_string_1, random_string_2);
     try {
         (void)RPCConvertNamedValues(random_string_1, random_string_vector);
diff --git a/src/test/util/setup_common.cpp b/src/test/util/setup_common.cpp
index 03ab3f523d..2035941ac6 100644
--- a/src/test/util/setup_common.cpp
+++ b/src/test/util/setup_common.cpp
@@ -77,6 +77,7 @@ BasicTestingSetup::BasicTestingSetup(const std::string& chainName, const std::ve
         {
             "dummy",
             "-printtoconsole=0",
+            "-logsourcelocations",
             "-logtimemicros",
             "-logthreadnames",
             "-debug",
diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index dccbf00d6f..845854bd4b 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -2201,4 +2201,17 @@ BOOST_AUTO_TEST_CASE(message_hash)
     BOOST_CHECK_NE(message_hash1, signature_hash);
 }
 
+BOOST_AUTO_TEST_CASE(remove_prefix)
+{
+    BOOST_CHECK_EQUAL(RemovePrefix("./util/system.h", "./"), "util/system.h");
+    BOOST_CHECK_EQUAL(RemovePrefix("foo", "foo"), "");
+    BOOST_CHECK_EQUAL(RemovePrefix("foo", "fo"), "o");
+    BOOST_CHECK_EQUAL(RemovePrefix("foo", "f"), "oo");
+    BOOST_CHECK_EQUAL(RemovePrefix("foo", ""), "foo");
+    BOOST_CHECK_EQUAL(RemovePrefix("fo", "foo"), "fo");
+    BOOST_CHECK_EQUAL(RemovePrefix("f", "foo"), "f");
+    BOOST_CHECK_EQUAL(RemovePrefix("", "foo"), "");
+    BOOST_CHECK_EQUAL(RemovePrefix("", ""), "");
+}
+
 BOOST_AUTO_TEST_SUITE_END()