From a3d78ef61a277b0b62dc93daf84756dfa7625d3d Mon Sep 17 00:00:00 2001
From: Ivan Topolnjak <ivantopo@gmail.com>
Date: Thu, 25 May 2017 16:52:52 +0200
Subject: trying to flatten out the structure and eliminate the notion of
 entitites

---
 .../src/main/scala/kamon/metric/Filter.scala       | 110 +++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 kamon-core/src/main/scala/kamon/metric/Filter.scala

(limited to 'kamon-core/src/main/scala/kamon/metric/Filter.scala')

diff --git a/kamon-core/src/main/scala/kamon/metric/Filter.scala b/kamon-core/src/main/scala/kamon/metric/Filter.scala
new file mode 100644
index 00000000..3ad4f7bd
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/metric/Filter.scala
@@ -0,0 +1,110 @@
+package kamon
+package metric
+
+import java.util.regex.Pattern
+import com.typesafe.config.Config
+
+object Filter {
+  def fromConfig(config: Config): Filter = {
+    val filtersConfig = config.getConfig("kamon.metric.filters")
+    val acceptUnmatched = filtersConfig.getBoolean("accept-unmatched")
+
+    val perMetricFilter = filtersConfig.firstLevelKeys.filter(_ != "accept-unmatched") map { metricName: String ⇒
+      val includes = readFilters(filtersConfig, s"$metricName.includes")
+      val excludes = readFilters(filtersConfig, s"$metricName.excludes")
+
+      (metricName, new IncludeExcludeNameFilter(includes, excludes))
+    } toMap
+
+    new Filter(perMetricFilter, acceptUnmatched)
+  }
+
+  private def readFilters(filtersConfig: Config, name: String): Seq[NameFilter] = {
+    import scala.collection.JavaConverters._
+    if(filtersConfig.hasPath(name))
+      filtersConfig.getStringList(name).asScala.map(readNameFilter)
+    else
+      Seq.empty
+  }
+
+  private def readNameFilter(pattern: String): NameFilter = {
+    if(pattern.startsWith("regex:"))
+      new RegexNameFilter(pattern.drop(6))
+    else if(pattern.startsWith("glob:"))
+      new GlobPathFilter(pattern.drop(5))
+    else
+      new GlobPathFilter(pattern)
+  }
+}
+
+class Filter(perMetricFilter: Map[String, NameFilter], acceptUnmatched: Boolean) {
+  def accept(metricName: String, pattern: String): Boolean =
+    perMetricFilter
+      .get(metricName)
+      .map(_.accept(pattern))
+      .getOrElse(acceptUnmatched)
+}
+
+trait NameFilter {
+  def accept(name: String): Boolean
+}
+
+class IncludeExcludeNameFilter(includes: Seq[NameFilter], excludes: Seq[NameFilter]) extends NameFilter {
+  override def accept(name: String): Boolean =
+    includes.exists(_.accept(name)) && !excludes.exists(_.accept(name))
+}
+
+class RegexNameFilter(pattern: String) extends NameFilter {
+  private val pathRegex = pattern.r
+
+  override def accept(name: String): Boolean = name match {
+    case pathRegex(_*) ⇒ true
+    case _             ⇒ false
+  }
+}
+
+class GlobPathFilter(glob: String) extends NameFilter {
+  private val globPattern = Pattern.compile("(\\*\\*?)|(\\?)|(\\\\.)|(/+)|([^*?]+)")
+  private val compiledPattern = getGlobPattern(glob)
+
+  override def accept(name: String): Boolean =
+    compiledPattern.matcher(name).matches()
+
+  private def getGlobPattern(glob: String) = {
+    val patternBuilder = new StringBuilder
+    val matcher = globPattern.matcher(glob)
+    while (matcher.find()) {
+      val (grp1, grp2, grp3, grp4) = (matcher.group(1), matcher.group(2), matcher.group(3), matcher.group(4))
+      if (grp1 != null) {
+        // match a * or **
+        if (grp1.length == 2) {
+          // it's a *workers are able to process multiple metrics*
+          patternBuilder.append(".*")
+        }
+        else {
+          // it's a *
+          patternBuilder.append("[^/]*")
+        }
+      }
+      else if (grp2 != null) {
+        // match a '?' glob pattern; any non-slash character
+        patternBuilder.append("[^/]")
+      }
+      else if (grp3 != null) {
+        // backslash-escaped value
+        patternBuilder.append(Pattern.quote(grp3.substring(1)))
+      }
+      else if (grp4 != null) {
+        // match any number of / chars
+        patternBuilder.append("/+")
+      }
+      else {
+        // some other string
+        patternBuilder.append(Pattern.quote(matcher.group))
+      }
+    }
+
+    Pattern.compile(patternBuilder.toString)
+  }
+}
+
-- 
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