package kamon.tag
import kamon.tag.TagSet.Lookup
import java.lang.{Boolean => JBoolean, Long => JLong, String => JString}
import java.util.function.BiConsumer
import org.eclipse.collections.impl.map.mutable.UnifiedMap
import org.slf4j.LoggerFactory
/**
* A immutable collection of key/value pairs with specialized support for storing String keys pointing to String, Long
* and/or Boolean values.
*
* Instances of Tags store all pairs in the same data structure, but preserving type information for the stored pairs
* and providing a simple DSL for accessing those values and expressing type expectations. It is also possible to
* lookup pairs without prescribing a mechanism for handling missing values. I.e. users of this class can decide
* whether to receive a null, java.util.Optional, scala.Option or any other value when looking up a pair.
*
* TagSet instances can only be created from the builder functions on the TagSet companion object. There are two
* different options to read the contained pairs from a Tags instance:
*
* 1. Using the lookup DSL. You can use the Lookup DSL when you know exactly that you are trying to get out of the
* tags instance. The lookup DSL is biased towards String keys since they are by far the most common case. For
* example, to get a given tag as an Option[String] and another as an Option[Boolean] the following code should
* suffice:
*
* import kamon.tag.Tags.Lookup._
* val tags = Tags.from(tagMap)
* val name = tags.get(option("name"))
* val isSignedIn = tags.get(booleanOption("isSignedIn"))
*
* 2. Using the .all() and .iterator variants. This option requires you to test the returned instances to verify
* whether they are a Tag.String, Tag.Long or Tag.Boolean instance and act accordingly. Fortunately this
* cumbersome operation is rarely necessary on user-facing code.
*
*/
class TagSet private(private val _underlying: UnifiedMap[String, Any]) {
import TagSet.withPair
/**
* Creates a new TagSet instance that includes the provided key/value pair. If the provided key was already associated
* with another value then the previous value will be discarded and overwritten with the provided one.
*/
def withTag(key: String, value: JString): TagSet =
withPair(this, key, value)
/**
* Creates a new TagSet instance that includes the provided key/value pair. If the provided key was already associated
* with another value then the previous value will be discarded and overwritten with the provided one.
*/
def withTag(key: String, value: JBoolean): TagSet =
withPair(this, key, value)
/**
* Creates a new TagSet instance that includes the provided key/value pair. If the provided key was already associated
* with another value then the previous value will be discarded and overwritten with the provided one.
*/
def withTag(key: String, value: JLong): TagSet =
withPair(this, key, value)
/**
* Creates a new TagSet instance that includes all the tags from the provided Tags instance. If any of the tags in this
* instance are associated to a key present on the provided instance then the previous value will be discarded and
* overwritten with the provided one.
*/
def withTags(other: TagSet): TagSet =
and(other)
/**
* Creates a new TagSet instance that includes the provided key/value pair. If the provided key was already associated
* with another value then the previous value will be discarded and overwritten with the provided one.
*/
def and(key: String, value: JString): TagSet =
withPair(this, key, value)
/**
* Creates a new TagSet instance that includes the provided key/value pair. If the provided key was already associated
* with another value then the previous value will be discarded and overwritten with the provided one.
*/
def and(key: String, value: JBoolean): TagSet =
withPair(this, key, value)
/**
* Creates a new TagSet instance that includes the provided key/value pair. If the provided key was already associated
* with another value then the previous value will be discarded and overwritten with the provided one.
*/
def and(key: String, value: JLong): TagSet =
withPair(this, key, value)
/**
* Creates a new TagSet instance that includes all the tags from the provided Tags instance. If any of the tags in this
* instance are associated to a key present on the provided instance then the previous value will be discarded and
* overwritten with the provided one.
*/
def and(other: TagSet): TagSet = {
val mergedMap = new UnifiedMap[String, Any](other._underlying.size() + this._underlying.size())
mergedMap.putAll(this._underlying)
mergedMap.putAll(other._underlying)
new TagSet(mergedMap)
}
/**
* Returns whether this TagSet instance does not contain any tags.
*/
def isEmpty(): Boolean =
_underlying.isEmpty
/**
* Returns whether this TagSet instance contains any tags.
*/
def nonEmpty(): Boolean =
!_underlying.isEmpty
/**
* Executes a tag lookup. The return type of this function will depend on the provided Lookup. Take a look at the
* built-in lookups on the [[Lookups]] companion object for more information.
*/
def get[T](lookup: Lookup[T]): T =
lookup.execute(_storage)
/**
* Returns a immutable sequence of tags created from the contained tags internal representation. Calling this method
* will cause the creation of a new data structure. Unless you really need to have all the tags as immutable
* instances it is recommended to use the .iterator() function instead.
*
* The returned sequence contains immutable values and is safe to share across threads.
*/
def all(): Seq[Tag] = {
var tags: List[Tag] = Nil
_underlying.forEach(new BiConsumer[String, Any] {
override def accept(key: String, value: Any): Unit = value match {
case v: String => tags = new TagSet.immutable.String(key, v) :: tags
case v: Boolean => tags = new TagSet.immutable.Boolean(key, v) :: tags
case v: Long => tags = new TagSet.immutable.Long(key, v) :: tags
}
})
tags
}
/**
* Returns an iterator of tags. The underlying iterator reuses the Tag instances to avoid unnecessary intermediate
* allocations and thus, it is not safe to share across threads. The most common case for tags iterators is on
* reporters which will need to iterate through all existent tags only to copy their values into a separate data
* structure that will be sent to the external systems.
*/
def iterator(): Iterator[Tag] = new Iterator[Tag] {
private val _entriesIterator = _underlying.keyValuesView().iterator()
private var _longTag: TagSet.mutable.Long = null
private var _stringTag: TagSet.mutable.String = null
private var _booleanTag: TagSet.mutable.Boolean = null
override def hasNext: Boolean =
_entriesIterator.hasNext
override def next(): Tag = {
val pair = _entriesIterator.next()
pair.getTwo match {
case v: String => stringTag(pair.getOne, v)
case v: Boolean => booleanTag(pair.getOne, v)
case v: Long => longTag(pair.getOne, v)
}
}
private def stringTag(key: JString, value: JString): Tag.String =
if(_stringTag == null) {
_stringTag = new TagSet.mutable.String(key, value)
_stringTag
} else _stringTag.updated(key, value)
private def booleanTag(key: JString, value: JBoolean): Tag.Boolean =
if(_booleanTag == null) {
_booleanTag = new TagSet.mutable.Boolean(key, value)
_booleanTag
} else _booleanTag.updated(key, value)
private def longTag(key: JString, value: JLong): Tag.Long =
if(_longTag == null) {
_longTag = new TagSet.mutable.Long(key, value)
_longTag
} else _longTag.updated(key, value)
}
override def equals(other: Any): Boolean =
other != null && other.isInstanceOf[TagSet] && other.asInstanceOf[TagSet]._underlying == _underlying
override def hashCode(): Int =
_underlying.hashCode()
override def toString: JString = {
val sb = new StringBuilder()
sb.append("Tags{")
var hasTags = false
val iterator = _underlying.keyValuesView().iterator()
while(iterator.hasNext) {
val pair = iterator.next()
if(hasTags)
sb.append(",")
sb.append(pair.getOne)
.append("=")
.append(pair.getTwo)
hasTags = true
}
sb.append("}").toString()
}
private val _storage = new TagSet.Storage {
override def get(key: String): Any = _underlying.get(key)
override def iterator(): Iterator[Tag] = TagSet.this.iterator()
override def isEmpty(): Boolean = _underlying.isEmpty
}
}
object TagSet {
/**
* Describes a strategy to lookup values from a TagSet instance. Implementations of this interface will be provided
* with the actual data structure containing the tags and must perform any necessary runtime type checks to ensure
* that the returned value is in assignable to the expected type T.
*
* Several implementation are provided in the Lookup companion object and it is recommended to import and use those
* definitions when looking up keys from a Tags instance.
*/
trait Lookup[T] {
/**
* Tries to find a value on a TagSet.Storage and returns a representation of it. In some cases the stored object
* might be returned as-is, in some others it might be transformed or wrapped on Option/Optional to handle missing
* values. Take a look at the Lookups companion object for examples..
*/
def execute(storage: TagSet.Storage): T
}
/**
* A temporary structure that accumulates key/value and creates a new TagSet instance from them. It is faster to use
* a Builder and add tags to it rather than creating TagSet and add each key individually. Builder instances rely on
* internal mutable state and are not thread safe.
*/
trait Builder {
/** Adds a new key/value pair to the builder. */
def add(key: String, value: Any): Builder
/** Creates a new TagSet instance that includes all valid key/value pairs added to this builder. */
def create(): TagSet
}
/**
* Abstracts the actual storage used for a TagSet. This interface resembles a stripped down interface of an immutable
* map of String to Any, used to expose the underlying structure where tags are stored to Lookups, without leaking
* the actual implementation.
*/
trait Storage {
/**
* Gets the value associated with the provided key, or null if no value was found. The decision of returning null
* when the key is not present is a conscious one, backed by the fact that users will never be exposed to this
* storage interface and they can decide their way of handling missing values by selecting an appropriate lookup.
*/
def get(key: String): Any
/**
* Provides an Iterator that can go through all key/value pairs contained in the Storage instance.
*/
def iterator(): Iterator[Tag]
/**
* Returns true if there are no tags in the storage.
*/
def isEmpty(): Boolean
}
/**
* A valid instance of tags that doesn't contain any pairs.
*/
val Empty = new TagSet(UnifiedMap.newMap[String, Any]())
/**
* Creates a new Builder instance.
*/
def builder(): Builder = new Builder {
private var _tagCount = 0
private var _tags: List[(String, Any)] = Nil
override def add(key: String, value: Any): Builder = {
if(isValidPair(key, value)) {
_tagCount += 1
_tags = (key -> value) :: _tags
}
this
}
override def create(): TagSet = {
val newMap = new UnifiedMap[String, Any](_tagCount)
_tags.foreach { case (key, value) => newMap.put(key, value) }
new TagSet(newMap)
}
}
/**
* Construct a new TagSet instance with a single key/value pair.
*/
def from(key: String, value: JString): TagSet =
withPair(Empty, key, value)
/**
* Construct a new TagSet instance with a single key/value pair.
*/
def from(key: String, value: JBoolean): TagSet =
withPair(Empty, key, value)
/**
* Construct a new TagSet instance with a single key/value pair.
*/
def from(key: String, value: JLong): TagSet =
withPair(Empty, key, value)
/**
* Constructs a new TagSet instance from a Map. The returned TagSet will only contain the entries that have String,
* Long or Boolean values from the supplied map, any other entry in the map will be ignored.
*/
def from(map: Map[String, Any]): TagSet = {
val unifiedMap = new UnifiedMap[String, Any](map.size)
map.foreach { pair => if(isValidPair(pair._1, pair._2)) unifiedMap.put(pair._1, pair._2)}
new TagSet(unifiedMap)
}
/**
* Constructs a new TagSet instance from a Map. The returned TagSet will only contain the entries that have String,
* Long or Boolean values from the supplied map, any other entry in the map will be ignored.
*/
def from(map: java.util.Map[String, Any]): TagSet = {
val unifiedMap = new UnifiedMap[String, Any](map.size)
map.forEach(new BiConsumer[String, Any] {
override def accept(key: String, value: Any): Unit =
if(isValidPair(key, value)) unifiedMap.put(key, value)
})
new TagSet(unifiedMap)
}
private val _logger = LoggerFactory.getLogger(classOf[TagSet])
private def withPair(parent: TagSet, key: String, value: Any): TagSet =
if(isValidPair(key, value)) {
val mergedMap = new UnifiedMap[String, Any](parent._underlying.size() + 1)
mergedMap.putAll(parent._underlying)
mergedMap.put(key, value)
new TagSet(mergedMap)
} else
parent
private def isValidPair(key: String, value: Any): Boolean = {
val isValidKey = key != null && key.nonEmpty
val isValidValue = isAllowedTagValue(value)
val isValid = isValidKey && isValidValue
if(!isValid && _logger.isDebugEnabled) {
if(!isValidKey && !isValidValue)
_logger.debug(s"Dismissing tag with invalid key [$key] and invalid value [$value]")
else if(!isValidKey)
_logger.debug(s"Dismissing tag with invalid key [$key] and value [$value]")
else
_logger.debug(s"Dismissing tag with key [$key] and invalid value [$value]")
}
isValid
}
private def isAllowedTagValue(v: Any): Boolean =
v != null && (v.isInstanceOf[String] || v.isInstanceOf[Boolean] || v.isInstanceOf[Long])
private object immutable {
case class String(key: JString, value: JString) extends Tag.String
case class Boolean(key: JString, value: JBoolean) extends Tag.Boolean
case class Long(key: JString, value: JLong) extends Tag.Long
}
private object mutable {
case class String(var key: JString, var value: JString) extends Tag.String with Updateable[JString]
case class Boolean(var key: JString, var value: JBoolean) extends Tag.Boolean with Updateable[JBoolean]
case class Long(var key: JString, var value: JLong) extends Tag.Long with Updateable[JLong]
trait Updateable[T] {
var key: JString
var value: T
def updated(key: JString, value: T): this.type = {
this.key = key
this.value = value
this
}
}
}
}
