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()