diff options
| author | w00t <w00t@e03df62e-2008-0410-955e-edbf42e46eb7> | 2008-07-02 14:20:38 +0000 |
|---|---|---|
| committer | w00t <w00t@e03df62e-2008-0410-955e-edbf42e46eb7> | 2008-07-02 14:20:38 +0000 |
| commit | f4ea51671f367d6e473049d52919a3c879329c6f (patch) | |
| tree | 1cfd0b16185ae251f3db8fad2a66e07190e7fa8b /include/linebuffer.h | |
| parent | b928a79eebfc9d87d84886185aba4a75705e221a (diff) | |
Forward port r9946: make SVSHOLD silent to avoid useless irritation to opers
git-svn-id: http://svn.inspircd.org/repository/trunk/inspircd@9947 e03df62e-2008-0410-955e-edbf42e46eb7
Diffstat (limited to 'include/linebuffer.h')
| -rw-r--r-- | include/linebuffer.h | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/include/linebuffer.h b/include/linebuffer.h new file mode 100644 index 000000000..8b579c452 --- /dev/null +++ b/include/linebuffer.h @@ -0,0 +1,110 @@ +/* +------------------------------------+
+ * | Inspire Internet Relay Chat Daemon |
+ * +------------------------------------+
+ *
+ * InspIRCd: (C) 2002-2008 InspIRCd Development Team
+ * See: http://www.inspircd.org/wiki/index.php/Credits
+ *
+ * This program is free but copyrighted software; see
+ * the file COPYING for details.
+ *
+ * ---------------------------------------------------
+ */
+
+/** Right, Line Buffers. Time for an explanation as to how sendqs work. By the way, ircd people,
+ * before you jump up and down screaming, this is not anything like Adrian Chadd's linebuffer
+ * stuff done for hybrid(and never really completed.) Rather, this is (I think) where linebuffer
+ * was heading, and should have been.
+ *
+ * Enough introduction, actual explanation starts here.
+ * In IRCd, we have a sendq. Traditionally, a sendq has been a big string. Stuff is tacked onto
+ * the end, and when we can, we send the user some data off the start of it. A circular buffer.
+ *
+ * This model works okay, and is quite simplistic to code, but has a drawback in that most IRC
+ * messages are multicast: topic changes, joins, parts, channel messages, and so on.
+ * This means that for each of these messages, we must do O(n^n) amount of work: bytes ^ recipients
+ * of writes will be made to sendqs, and this is a slow and expensive operation.
+ *
+ * The solution comes with the use of this linebuffer class below, which is managed entirely by
+ * the user class (though it *may* be possible to add a server to server implementation of this later,
+ * but that's nowhere near so needed, and nowhere near so trivial, thanks to the inherited nature
+ * of buffered socket, but I digress).
+ *
+ * What this class does, in a nutshell:
+ * When we need to send a message to a user, we create a LineBuffer object. It has a reference count, and
+ * we copy the string we need to send into the LineBuffer object also.
+ * We then tack a pointer to this LineBuffer into an std::list stored in the User class.
+ * When the user writes data, a ptr is advanced depending how much of that line they wrote. If they wrote all
+ * of the line, the pointer is popped off the std::list, the ptr is reset, and the buffer's refcount is
+ * decremented - and if it reaches 0, the linebuffer is destroyed as it has fulfilled it's purpose.
+ *
+ * Effectively, this means that multicast writes become O(n) + time taken to copy message once, or just about.
+ *
+ * We gain efficiency, and much, much better RAM usage.
+ */
+static unsigned int totalbuffers = 0;
+
+class LineBuffer
+{
+ private:
+ std::string msg;
+ unsigned long refcount;
+
+ // Don't let it be copied.
+ LineBuffer(const LineBuffer &) { }
+
+ public:
+ ~LineBuffer()
+ {
+ totalbuffers--;
+ printf("Destroying LineBuffer with %u bytes, total buffers is %u\n", msg.length(), totalbuffers);
+ msg.resize(0);
+ }
+
+ LineBuffer(std::string &m)
+ {
+ if (m.length() > MAXBUF - 2) /* MAXBUF has a value of 514, to account for line terminators */
+ {
+ // Trim the message to fit, 510 characters max.
+ m = m.substr(0, MAXBUF - 4); // MAXBUF is 514, we need 510.
+ }
+
+ // Add line terminator
+ m.append("\r\n");
+
+ // And copy
+ msg = m;
+ refcount = 0;
+ totalbuffers++;
+ printf("Creating LineBuffer with %u bytes, total buffers is %u\n", msg.length(), totalbuffers);
+ }
+
+ std::string &GetMessage()
+ {
+ return msg;
+ }
+
+ unsigned long GetMessageLength()
+ {
+ return msg.length();
+ }
+
+ // To be used after creation, when we know how many recipients we actually have.
+ void SetRefcount(unsigned long r)
+ {
+ refcount = r;
+ }
+
+ unsigned long DecrementCount()
+ {
+ if (refcount == 0)
+ {
+ throw "decrementing a refcount when nobody is using it is weird and wrong";
+ }
+
+ refcount--;
+ return refcount;
+ }
+
+ // There is no increment method as it isn't really needed.
+};
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