Add http pool to reduce connection overhead

src/apiutils.nim

@@ -1,9 +1,11 @@
 import httpclient, asyncdispatch, options, times, strutils, uri
 import packedjson
-import types, tokens, consts, parserutils
+import types, tokens, consts, parserutils, http_pool
 
 const rl = "x-rate-limit-"
 
+var pool {.threadvar.}: HttpPool
+
 proc genParams*(pars: openarray[(string, string)] = @[]; cursor="";
                 count="20"; ext=true): seq[(string, string)] =
   result = timelineParams
@@ -18,6 +20,7 @@ proc genParams*(pars: openarray[(string, string)] = @[]; cursor="";
 
 proc genHeaders*(token: Token = nil): HttpHeaders =
   result = newHttpHeaders({
+    "connection": "keep-alive",
     "authorization": auth,
     "content-type": "application/json",
     "x-guest-token": if token == nil: "" else: token.tok,
@@ -29,14 +32,17 @@ proc genHeaders*(token: Token = nil): HttpHeaders =
   })
 
 proc fetch*(url: Uri; oldApi=false): Future[JsonNode] {.async.} =
+  once:
+    pool = HttpPool()
+
   var token = await getToken()
   if token.tok.len == 0:
     result = newJNull()
 
-  var client = newAsyncHttpClient(headers=genHeaders(token))
+  let headers = genHeaders(token)
   try:
     let
-      resp = await client.get($url)
+      resp = pool.use(headers): await c.get($url)
       body = await resp.body
 
     if body.startsWith('{') or body.startsWith('['):
@@ -54,5 +60,3 @@ proc fetch*(url: Uri; oldApi=false): Future[JsonNode] {.async.} =
   except Exception:
     echo "error: ", url
     result = newJNull()
-  finally:
-    client.close()

src/http_pool.nim

@@ -0,0 +1,37 @@
+import asyncdispatch, httpclient
+
+type
+  HttpPool* = ref object
+    conns*: seq[AsyncHttpClient]
+
+var maxConns {.threadvar.}: int
+
+let keepAlive* = newHttpHeaders({
+  "Connection": "Keep-Alive"
+})
+
+proc setMaxHttpConns*(n: int) =
+  maxConns = n
+
+proc release*(pool: HttpPool; client: AsyncHttpClient) =
+  if pool.conns.len >= maxConns:
+    client.close()
+  elif client != nil:
+    pool.conns.insert(client)
+
+template use*(pool: HttpPool; heads: HttpHeaders; body: untyped): untyped =
+  var c {.inject.}: AsyncHttpClient
+
+  if pool.conns.len == 0:
+    c = newAsyncHttpClient(headers=heads)
+  else:
+    c = pool.conns.pop()
+    c.headers = heads
+
+  try:
+    body
+  except ProtocolError:
+    # Twitter closed the connection, retry
+    body
+  finally:
+    pool.release(c)

src/nitter.nim

@@ -3,7 +3,7 @@ from net import Port
 
 import jester
 
-import types, config, prefs, formatters, redis_cache, tokens
+import types, config, prefs, formatters, redis_cache, http_pool, tokens
 import views/[general, about]
 import routes/[
   preferences, timeline, status, media, search, rss, list,
@@ -25,6 +25,7 @@ updateDefaultPrefs(fullCfg)
 setCacheTimes(cfg)
 setHmacKey(cfg.hmacKey)
 setProxyEncoding(cfg.base64Media)
+setMaxHttpConns(100)
 
 waitFor initRedisPool(cfg)
 stdout.write &"Connected to Redis at {cfg.redisHost}:{cfg.redisPort}\n"

src/parser.nim

@@ -114,7 +114,8 @@ proc parseVideo(js: JsonNode): Video =
     views: js{"ext", "mediaStats", "r", "ok", "viewCount"}.getStr,
     available: js{"ext_media_availability", "status"}.getStr == "available",
     title: js{"ext_alt_text"}.getStr,
-    durationMs: js{"duration_millis"}.getInt
+    durationMs: js{"duration_millis"}.getInt,
+    playbackType: mp4
   )
 
   with title, js{"additional_media_info", "title"}:

src/tokens.nim

@@ -1,7 +1,8 @@
 import asyncdispatch, httpclient, times, sequtils, strutils, json
-import types, agents, consts
+import types, agents, consts, http_pool
 
 var
+  clientPool {.threadvar.}: HttpPool
   tokenPool {.threadvar.}: seq[Token]
   lastFailed: Time
   minFail = initDuration(seconds=10)
@@ -10,22 +11,20 @@ proc fetchToken(): Future[Token] {.async.} =
   if getTime() - lastFailed < minFail:
     return Token()
 
-  let
-    headers = newHttpHeaders({
-      "accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
-      "accept-language": "en-US,en;q=0.5",
-      "connection": "keep-alive",
-      "user-agent": getAgent(),
-      "authorization": auth
-    })
-    client = newAsyncHttpClient(headers=headers)
+  let headers = newHttpHeaders({
+    "accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
+    "accept-language": "en-US,en;q=0.5",
+    "connection": "keep-alive",
+    "user-agent": getAgent(),
+    "authorization": auth
+  })
 
   var
     resp: string
     tok: string
 
   try:
-    resp = await client.postContent(activate)
+    resp = clientPool.use(headers): await c.postContent(activate)
     tok = parseJson(resp)["guest_token"].getStr
 
     let time = getTime()
@@ -35,8 +34,6 @@ proc fetchToken(): Future[Token] {.async.} =
     lastFailed = getTime()
     echo "fetching token failed: ", e.msg
     result = Token()
-  finally:
-    client.close()
 
 proc expired(token: Token): bool {.inline.} =
   const
@@ -74,6 +71,8 @@ proc poolTokens*(amount: int) {.async.} =
     release(await token)
 
 proc initTokenPool*(cfg: Config) {.async.} =
+  clientPool = HttpPool()
+
   while true:
     if tokenPool.countIt(not it.isLimited) < cfg.minTokens:
       await poolTokens(min(4, cfg.minTokens - tokenPool.len))