add input filter for umem_cache bufctl stacks

lib/input-umem-cache.js

@@ -0,0 +1,121 @@
+/*
+ * lib/input-umem-cache.js: reads output from an mdb ::bufctl -v, which emits
+ * stanzas that look like this:
+ *
+ *        ffeca50         10001000   401f50b1339a6a                1
+ *                         8f73010                0                0
+ *                libumem.so.1`umem_cache_alloc_debug+0x144
+ *                libumem.so.1`umem_cache_alloc+0x19a
+ *                libumem.so.1`umem_alloc+0xcd
+ *                libumem.so.1`malloc+0x2a
+ *                libstdc++.so.6.0.17`_Znwj+0x29
+ *                libstdc++.so.6.0.17`_Znaj+0x1d
+ *                _ZN2v88internal11HandleScope6ExtendEv+0xdf
+ *                _ZN2v88internal8JSObject20SetPropertyForResultEPNS0_12LookupResultEPNS0_6StringEPNS0_6ObjectE18PropertyAttributesNS0_14StrictModeFlagENS0_10JSReceiver14StoreFromKeyedE+0x5f8
+ *                _ZN2v88internal10JSReceiver11SetPropertyEPNS0_6StringEPNS0_6ObjectE18PropertyAttributesNS0_14StrictModeFlagENS1_14StoreFromKeyedE+0x8d
+ *                _ZN2v88internal7StoreIC5StoreENS0_16InlineCacheStateENS0_14StrictModeFlagENS0_6HandleINS0_6ObjectEEENS4_INS0_6StringEEES6_+0x359
+ *                _ZN2v88internal12StoreIC_MissENS0_9ArgumentsEPNS0_7IsolateE+0x139
+ *                0xa3c0a376
+ *                0xbf54e125
+ *                0xbf573d62
+ *                0xbf573c93
+ *
+ * You can generate such output with:
+ *
+ *	> ::walk bufctl | ::bufctl -v ! cat > stacks.out
+ */
+
+
+var mod_util = require('util');
+var mod_events = require('events');
+
+var mod_carrier = require('carrier');
+
+/* We always ignore the first 2 lines. */
+var NHEADERLINES = 2;
+
+exports.reader = UmemStreamReader;
+
+function UmemStreamReader(input, log)
+{
+	this.dsr_log = log;
+	this.dsr_linenum = 0;
+	this.dsr_sline = 0;
+	this.dsr_stack = [];
+	this.dsr_carrier = mod_carrier.carry(input);
+	this.dsr_carrier.on('line', this.onLine.bind(this));
+	this.dsr_carrier.on('end', this.onEnd.bind(this));
+
+	mod_events.EventEmitter.call(this);
+}
+
+mod_util.inherits(UmemStreamReader, mod_events.EventEmitter);
+
+UmemStreamReader.prototype.onLine = function (line)
+{
+	/* The first two lines are always ignored. */
+	if (++this.dsr_linenum <= NHEADERLINES)
+		return;
+
+	/* ignore ADDR, BUFADDR, TIMESTAMP, THREAD, CACHE, LASTLOG, CONTENTS */
+	if (++this.dsr_sline <= NHEADERLINES)
+		return;
+
+	if (!line.trim()) {
+		if (this.dsr_stack.length === 0) {
+			this.dsr_log.warn('line ' + this.dsr_linenum +
+			    ': found count with no stack');
+			return;
+		}
+
+		this.emit('stack', this.dsr_stack, 1);
+		this.dsr_stack = [];
+		this.dsr_sline = 0;
+		return;
+	}
+
+	/*
+	 * In general, lines may have leading or trailing whitespace and the
+	 * following components:
+	 *
+	 *	module`function+offset
+	 *
+	 * We try to avoid assuming too much about the form in order to support
+	 * various annotations provided by ustack helpers, but we want to strip
+	 * off the offset.
+	 */
+	var frame = line;
+	frame = frame.replace(/^\s+/, '');
+	frame = frame.replace(/\s+$/, '');
+	/* JSSTYLED */
+	frame = frame.replace(/\+.*/, '');
+
+	/* maybe configurable? */
+	frame = frame.replace(/^0x[a-f0-9]{8}$/, '<unknown>');
+
+	/*
+	 * Remove both function and template parameters from demangled C++
+	 * frames, but skip the first two characters because they're used by the
+	 * Node.js ustack helper as separators.
+	 */
+	/* JSSTYLED */
+	frame = frame.replace(/(..)[(<].*/, '$1');
+
+	if (line.length === 0) {
+		if (this.dsr_stack.length !== 0)
+			this.dsr_log.warn('line ' + this.dsr_linenum +
+			    ': unexpected blank line');
+		return;
+	}
+
+	this.dsr_stack.unshift(frame);
+};
+
+UmemStreamReader.prototype.onEnd = function ()
+{
+	if (this.dsr_stack.length !== 0)
+		this.dsr_log.warn('line ' + this.dsr_linenum +
+		    ': unexpected end of stream');
+
+	this.emit('end');
+};