1 files changed, 110 insertions, 0 deletions
diff --git a/kamon-core/src/main/scala/kamon/metric/EntityFilter.scala b/kamon-core/src/main/scala/kamon/metric/EntityFilter.scala
new file mode 100644
index 00000000..cf203609
--- /dev/null
+++ b/kamon-core/src/main/scala/kamon/metric/EntityFilter.scala
@@ -0,0 +1,110 @@
+package kamon
+package metric
+
+import java.util.regex.Pattern
+import com.typesafe.config.Config
+
+object EntityFilter {
+  def fromConfig(config: Config): EntityFilter = {
+    val filtersConfig = config.getConfig("kamon.metric.filters")
+    val acceptUnmatched = filtersConfig.getBoolean("accept-unmatched")
+
+    val perCategoryFilters = filtersConfig.firstLevelKeys.filter(_ != "accept-unmatched") map { category: String ⇒
+      val includes = readFilters(filtersConfig, s"$category.includes")
+      val excludes = readFilters(filtersConfig, s"$category.excludes")
+
+      (category, new IncludeExcludeNameFilter(includes, excludes, acceptUnmatched))
+    } toMap
+
+    new EntityFilter(perCategoryFilters, 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 EntityFilter(perCategoryFilters: Map[String, NameFilter], acceptUnmatched: Boolean) {
+  def accept(entity: Entity): Boolean =
+    perCategoryFilters
+      .get(entity.category)
+      .map(_.accept(entity.name))
+      .getOrElse(acceptUnmatched)
+}
+
+trait NameFilter {
+  def accept(name: String): Boolean
+}
+
+class IncludeExcludeNameFilter(includes: Seq[NameFilter], excludes: Seq[NameFilter], acceptUnmatched: Boolean) extends NameFilter {
+  override def accept(name: String): Boolean =
+    (includes.exists(_.accept(name)) || acceptUnmatched) && !excludes.exists(_.accept(name))
+}
+
+class RegexNameFilter(path: String) extends NameFilter {
+  private val pathRegex = path.r
+
+  override def accept(path: String): Boolean = path 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)
+  }
+}
+