add stream metrics (#136)

* add stream metrics

- just BufferStream and Connection are tracked, for now
- flag checking is enforced more strictly in close(), since it became
  clear that instances are closed multiple times

* add "metrics" dependency

and sort the list

libp2p.nimble

@@ -8,11 +8,12 @@ license       = "MIT"
 skipDirs      = @["tests", "examples", "Nim"]
 
 requires "nim > 0.19.4",
-         "secp256k1",
-         "nimcrypto >= 0.4.1",
-         "chronos >= 2.3.8",
          "bearssl >= 0.1.4",
          "chronicles >= 0.7.1",
+         "chronos >= 2.3.8",
+         "metrics",
+         "nimcrypto >= 0.4.1",
+         "secp256k1",
          "stew"
 
 proc runTest(filename: string) =

libp2p/connection.nim

@@ -7,7 +7,8 @@
 ## This file may not be copied, modified, or distributed except according to
 ## those terms.
 
-import chronos, chronicles, oids
+import oids
+import chronos, chronicles, metrics
 import peerinfo,
        multiaddress,
        stream/lpstream,
@@ -29,6 +30,8 @@ type
   InvalidVarintException = object of LPStreamError
   InvalidVarintSizeException = object of LPStreamError
 
+declareGauge libp2p_open_connection, "open Connection instances"
+
 proc newInvalidVarintException*(): ref InvalidVarintException =
   newException(InvalidVarintException, "Unable to parse varint")
 
@@ -57,6 +60,7 @@ proc init*[T: Connection](self: var T, stream: LPStream): T =
   when chronicles.enabledLogLevel == LogLevel.TRACE:
     self.oid = genOid()
   asyncCheck self.bindStreamClose()
+  libp2p_open_connection.inc()
 
   return self
 
@@ -117,11 +121,11 @@ method closed*(s: Connection): bool =
   result = s.stream.closed
 
 method close*(s: Connection) {.async, gcsafe.} =
+  if not s.closed:
     trace "about to close connection", closed = s.closed,
                                        peer = if not isNil(s.peerInfo):
                                          s.peerInfo.id else: ""
 
-  if not s.closed:
     if not isNil(s.stream) and not s.stream.closed:
       trace "closing child stream", closed = s.closed,
                                     peer = if not isNil(s.peerInfo):
@@ -134,6 +138,7 @@ method close*(s: Connection) {.async, gcsafe.} =
     trace "connection closed", closed = s.closed,
                                peer = if not isNil(s.peerInfo):
                                  s.peerInfo.id else: ""
+    libp2p_open_connection.dec()
 
 proc readLp*(s: Connection): Future[seq[byte]] {.async, gcsafe.} =
   ## read lenght prefixed msg

libp2p/protocols/secure/secure.nim

@@ -8,8 +8,7 @@
 ## those terms.
 
 import options
-import chronos
-import chronicles
+import chronos, chronicles
 import ../protocol,
        ../../stream/bufferstream,
        ../../crypto/crypto,

libp2p/stream/bufferstream.nim

@@ -31,7 +31,7 @@
 ## buffer goes below ``maxSize`` or more data becomes available.
 
 import deques, math, oids
-import chronos, chronicles
+import chronos, chronicles, metrics
 import ../stream/lpstream
 
 const DefaultBufferSize* = 1024
@@ -52,6 +52,8 @@ type
   AlreadyPipedError* = object of CatchableError
   NotWritableError* = object of CatchableError
 
+declareGauge libp2p_open_bufferstream, "open BufferStream instances"
+
 proc newAlreadyPipedError*(): ref Exception {.inline.} =
   result = newException(AlreadyPipedError, "stream already piped")
 
@@ -77,6 +79,8 @@ proc initBufferStream*(s: BufferStream,
   s.closeEvent = newAsyncEvent()
   when chronicles.enabledLogLevel == LogLevel.TRACE:
     s.oid = genOid()
+  s.isClosed = false
+  libp2p_open_bufferstream.inc()
 
 proc newBufferStream*(handler: WriteHandler = nil,
                       size: int = DefaultBufferSize): BufferStream =
@@ -386,6 +390,7 @@ proc `|`*(s: BufferStream, target: BufferStream): BufferStream =
 
 method close*(s: BufferStream) {.async.} =
   ## close the stream and clear the buffer
+  if not s.isClosed:
     trace "closing bufferstream"
     for r in s.readReqs:
       if not(isNil(r)) and not(r.finished()):
@@ -394,3 +399,5 @@ method close*(s: BufferStream) {.async.} =
     s.readBuf.clear()
     s.closeEvent.fire()
     s.isClosed = true
+    libp2p_open_bufferstream.dec()
+