From 927ff297cdf031054a1a76b392a509e186c5abae Mon Sep 17 00:00:00 2001
From: Norman Rzepka <code@normanrz.com>
Date: Sun, 12 Aug 2018 18:36:25 +0200
Subject: [PATCH] moar buffer

---
 Dockerfile   |  2 +-
 README.md    | 13 +++++++++----
 index.js     | 17 +++++++++++++----
 package.json |  1 +
 yarn.lock    |  4 ++++
 5 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index cefae5b..d67ff74 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -6,6 +6,6 @@ RUN yarn install
 
 ENV TILE_SET_CACHE 128
 ENV TILE_SET_PATH /app/data
-ENV MAX_POST_SIZE 500kb
+ENV MAX_POST_SIZE 700kb
 
 CMD ["yarn", "run", "start"]
diff --git a/README.md b/README.md
index 1d09ff0..694ee45 100644
--- a/README.md
+++ b/README.md
@@ -4,11 +4,12 @@ Elevation service that works with the [Terrain data provided on Amazon AWS S3](h
 
 Inspired by:
 
-* https://github.com/perliedman/elevation-service
-* https://github.com/perliedman/node-hgt
+- https://github.com/perliedman/elevation-service
+- https://github.com/perliedman/node-hgt
 
 ## API usage
-The service has a very simple API. Just post your latitude-longitude pairs as a JSON array to the service and receive an array of elevations as response. Maximum post payload is by default 500 KB.
+
+The service has a very simple API. Just post your latitude-longitude pairs as a JSON array to the service and receive an array of elevations as response. Maximum post payload is by default 700 KB (which fits roughly 10,000 points).
 
 ```bash
 # > [[lat, lng], ...]
@@ -19,11 +20,13 @@ curl -d '[[51.3, 13.4], [51.4, 13.3]]' -XPOST -H 'Content-Type: application/json
 ## Usage with pre-downloaded data
 
 Download data (ca. 200 GB):
+
 ```bash
 aws s3 cp --recursive s3://elevation-tiles-prod/skadi /path/to/data/folder
 ```
 
 Run the docker container:
+
 ```bash
 docker run --rm -v/path/to/data/folder:/app/data -p3000:3000 normanrz/elevation-service
 ```
@@ -31,9 +34,11 @@ docker run --rm -v/path/to/data/folder:/app/data -p3000:3000 normanrz/elevation-
 ## Usage with S3-hosted data
 
 Run the docker container:
+
 ```bash
 docker run --rm -eTILE_SET_PATH=s3:// -p3000:3000 normanrz/elevation-service
 ```
 
 ## License
-MIT
\ No newline at end of file
+
+MIT
diff --git a/index.js b/index.js
index b71e57d..1e19f81 100644
--- a/index.js
+++ b/index.js
@@ -1,9 +1,11 @@
 const { json, send } = require("micro");
+const limitedMap = require("limited-map");
 const { FileTileSet, S3TileSet } = require("./tileset");
 
 const cacheSize = process.env.TILE_SET_CACHE || 128;
 const tileFolder = process.env.TILE_SET_PATH || __dirname;
 const maxPostSize = process.env.MAX_POST_SIZE || "500kb";
+const maxParallelProcessing = 500;
 
 const tiles = tileFolder.startsWith("s3://")
   ? new S3TileSet({ cacheSize })
@@ -14,11 +16,18 @@ module.exports = async (req, res) => {
     return send(res, 405, { error: "Only POST allowed" });
   }
 
-  const geojson = await json(req, { limit: maxPostSize });
-  if (!geojson || Object.keys(geojson).length === 0) {
-    return send(res, 400, { error: "Invalid GeoJSON" });
+  const payload = await json(req, { limit: maxPostSize });
+  if (!payload || Object.keys(payload).length === 0) {
+    return send(res, 400, {
+      error:
+        "Invalid Payload. Expected a JSON array with latitude-longitude pairs: [[lat, lng], ...]"
+    });
   }
 
-  const result = await Promise.all(geojson.map(ll => tiles.getElevation(ll)));
+  const result = await limitedMap(
+    payload,
+    ll => tiles.getElevation(ll),
+    maxParallelProcessing
+  );
   return result;
 };
diff --git a/package.json b/package.json
index dac4ebe..56e2c33 100644
--- a/package.json
+++ b/package.json
@@ -10,6 +10,7 @@
   "author": "Norman Rzepka <code@normanrz.com>",
   "license": "MIT",
   "dependencies": {
+    "limited-map": "^0.0.1",
     "lru-memoize": "^1.0.2",
     "micro": "^9.3.2"
   },
diff --git a/yarn.lock b/yarn.lock
index 268fdcd..9e58f37 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -71,6 +71,10 @@ is-stream@1.1.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/is-stream/-/is-stream-1.1.0.tgz#12d4a3dd4e68e0b79ceb8dbc84173ae80d91ca44"
 
+limited-map@^0.0.1:
+  version "0.0.1"
+  resolved "https://registry.yarnpkg.com/limited-map/-/limited-map-0.0.1.tgz#78a24fd73b0fb58312f7d639ca572b1bfd3f0bf0"
+
 lru-memoize@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/lru-memoize/-/lru-memoize-1.0.2.tgz#f5ae84d288e7d55fec8388ec0bd725621bc815d0"