Difficult to customize logging behaviour #102
Comments
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The difficulty of customizing logging is noted. I'll try and address these in the next revision of the logging system. If anyone else has feedback on custom logging please leave them here. |
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Thanks for the response. It is in no way urgent or critical. I have made it work by making "print" virtual and created a derived class. This works for now. |
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ulfj's 'temporary' solution (overriding print()) works fine (and requires few changes) if you code the alevel and elevel constants as enums - you can then specialize on the 2 cases as ulf wanted. Here's a diff of the changes I made to make it possible to create a subclassed logger of my own. As far as I can see, few changes are required in the library code and no changes to library clients. Index: endpoint.hpp
===================================================================
--- endpoint.hpp (revision 20601)
+++ endpoint.hpp (working copy)
@@ -120,8 +120,8 @@
friend socket_type;
friend connection_type;
#else
- friend class role< endpoint<role,socket> >;
- friend class socket< endpoint<role,socket> >;
+ friend class role< endpoint<role,socket,logger> >;
+ friend class socket< endpoint<role,socket,logger> >;
friend class connection<type,role< type >::template connection,socket< type >::template connection>;
#endif
Index: logger/logger.hpp
===================================================================
--- logger/logger.hpp (revision 20601)
+++ logger/logger.hpp (working copy)
@@ -37,57 +37,61 @@
namespace log {
namespace alevel {
- typedef uint16_t value;
+typedef enum {
- static const value OFF = 0x0;
+ OFF = 0x0,
// A single line on connect with connecting ip, websocket version,
// request resource, user agent, and the response code.
- static const value CONNECT = 0x1;
+ CONNECT = 0x1,
// A single line on disconnect with wasClean status and local and remote
// close codes and reasons.
- static const value DISCONNECT = 0x2;
+ DISCONNECT = 0x2,
// A single line on incoming and outgoing control messages.
- static const value CONTROL = 0x4;
+ CONTROL = 0x4,
// A single line on incoming and outgoing frames with full frame headers
- static const value FRAME_HEADER = 0x10;
+ FRAME_HEADER = 0x10,
// Adds payloads to frame logs. Note these can be long!
- static const value FRAME_PAYLOAD = 0x20;
+ FRAME_PAYLOAD = 0x20,
// A single line on incoming and outgoing messages with metadata about type,
// length, etc
- static const value MESSAGE_HEADER = 0x40;
+ MESSAGE_HEADER = 0x40,
// Adds payloads to message logs. Note these can be long!
- static const value MESSAGE_PAYLOAD = 0x80;
+ MESSAGE_PAYLOAD = 0x80,
// Notices about internal endpoint operations
- static const value ENDPOINT = 0x100;
+ ENDPOINT = 0x100,
// DEBUG values
- static const value DEBUG_HANDSHAKE = 0x8000;
- static const value DEBUG_CLOSE = 0x4000;
- static const value DEVEL = 0x2000;
+ DEBUG_HANDSHAKE = 0x8000,
+ DEBUG_CLOSE = 0x4000,
+ DEVEL = 0x2000,
- static const value ALL = 0xFFFF;
+ ALL = 0xFFFF
+} value;
}
namespace elevel {
- typedef uint16_t value;
+typedef enum {
- static const value OFF = 0x0;
+ OFF = 0x0,
- static const value DEVEL = 0x1; // debugging
- static const value LIBRARY = 0x2; // library usage exceptions
- static const value INFO = 0x4; //
- static const value WARN = 0x8; //
- static const value RERROR = 0x10; // recoverable error
- static const value FATAL = 0x20; // unrecoverable error
+ DEVEL = 0x1, // debugging
+ LIBRARY = 0x2, // library usage exceptions
+ INFO = 0x4, //
+ WARN = 0x8, //
+ RERROR = 0x10, // recoverable error
+ FATAL = 0x20, // unrecoverable error
- static const value ALL = 0xFFFF;
+ ALL = 0xFFFF
+} value;
}
template <typename level_type>
class logger {
public:
+ virtual ~logger<level_type>() {}
+
template <typename T>
logger<level_type>& operator<<(T a) {
if (test_level(m_write_level)) {
@@ -105,7 +109,7 @@
}
void set_level(level_type l) {
- m_level |= l;
+ m_level = static_cast<level_type>(m_level | l);
}
void set_levels(level_type l1, level_type l2) {
@@ -129,7 +133,7 @@
}
}
- logger<level_type>& print() {
+ virtual logger<level_type>& print() {
if (test_level(m_write_level)) {
std::cout << m_prefix <<
boost::posix_time::to_iso_extended_string(
@@ -145,7 +149,7 @@
m_write_level = l;
return *this;
}
-private:
+protected:
std::ostringstream m_oss;
level_type m_write_level;
level_type m_level;Here's a sample of how I implemented it: namespace websocketpp
{
namespace log
{
template<typename level_type>
class my_logger : public logger<level_type>
{
virtual logger<level_type>& print();
};
template<>
logger<alevel::value>& my_logger<alevel::value>::print()
{
if (test_level(m_write_level))
{
LogVerbose ("WSK: " << m_oss.str());
m_oss.str("");
}
return *this;
}
template<>
logger<elevel::value>& my_logger<elevel::value>::print()
{
if (test_level(m_write_level))
{
switch(m_write_level)
{
case elevel::OFF:
break;
case elevel::DEVEL:
LogDebug ("WSK: " << m_oss.str());
break;
case elevel::LIBRARY:
case elevel::INFO:
LogVerbose ("WSK: " << m_oss.str());
break;
case elevel::WARN:
LogMessage ("WSK: " << m_oss.str());
break;
case elevel::RERROR:
case elevel::FATAL:
LogWarning ("WSK: " << m_oss.str());
break;
default:
LogWarning ("WSK: [unknown elevel " <<
m_write_level << "]: " << m_oss.str());
break;
}
m_oss.str("");
}
return *this;
}
}
typedef websocketpp::endpoint<
websocketpp::role::server,
websocketpp::socket::plain,
log::my_logger> server;
}
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How about adding support for external logging libraries. pion-net gives you the ability to build with support for several libraries. From git project page: https://github.com/cloudmeter/pion-net/tree/4.0.11 a) use std::cout and std::cerr for logging (the default configuration) Brian |
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some of these external logging libraries look quite interesting. I am going to try and get some preliminary support for external logging in version 0.3 |
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Hmm - I ended up building a client app after my fixes and one or 2 small IMHO - if you give us good support for applying our own logging, maybe you Best, Jim On 29 June 2012 21:27, Peter Thorson <
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This thread refers to issues related to the design of the logging policies in the 0.2.x branch, which will not be fixed. The 0.3.x+ logging policies were completely re-done and should allow for better logging customization. If anyone has further suggestions or issues with the customizability of 0.3.x+ logging they should open a new issue. |
I would like to suggest a small change to make it simpler to integrate logging with an application-wide logging facility.
The websocket++ logger class can be "replaced" by passing a parameter to the websocketpp::endpoint template:
This is good but there are some issues that may need some attention for this to reach its full usefullness.
The logger template class is instantiated twice in the endpoint (alog and elog) with template parameters log::alevel::value and log::elevel::value. These types resolves to the same uint16_t type making it difficult to use template specialization to give elog and alog different behaviour (at least on Windows using VS2010). This can be fixed in different ways. The very least I am looking for is to know if the level bits are alevel::value or elevel::value. This is because the logging filter will be in the outer logging framework.
Logging is done like this (example from library code):
The problem I have with this is the "log::endl" which is statement that causes the log to be printed. The log::endl function looks like:
This means that I see no way to get my own "print" function called short of making changes to the library (making print virtual) and deriving my logger class from the one in the library. A better way may perhaps be to replace log::endl with a function defined by the logger class (no virtual function call overhead) - example:
This way the custom logger should be possible to customize without changes to the library. I have not tested the changes I suggest so they may not be working.
Regards,
Ulf
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