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Adds 304 support by hashing response body to create an ETag. #1

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Adds 304 support by hashing response body to create an ETag. #1

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25 changes: 20 additions & 5 deletions index.js
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Original file line number Diff line number Diff line change
@@ -1,11 +1,17 @@
var adapterMemory = require('./lib/adapterMemory.js'),
var crypto = require('crypto')
adapterMemory = require('./lib/adapterMemory.js'),
adapterMemJS = require('./lib/adapterMemJS.js'),
adapterRedis = require('./lib/adapterRedis.js');


//returns a unique hash based on the passed string
var getHash = function(stringToHash) {
return crypto.createHash('sha256').update(stringToHash).digest('hex');
};

// Caching middleware for Express framework
// details are here https://github.com/vodolaz095/express-view-cache


module.exports=function(invalidateTimeInMilliseconds,parameters){
if(invalidateTimeInMilliseconds && /^\d+$/.test(invalidateTimeInMilliseconds)){
//it is ok
Expand All @@ -18,11 +24,19 @@ module.exports=function(invalidateTimeInMilliseconds,parameters){
if(parameters && parameters.type){
response.type(parameters.type);
}
if (request.method == 'GET') {
if (request.method === 'GET') {
cache.get(request.originalUrl,function(err,value){
if(value){
console.log('[CACHE] HIT: GET '+request.originalUrl);
response.header('Cache-Control', 'private, no-cache, no-store, must-revalidate')

var contentHash = getHash(value);
if (request.get('ETag') === contentHash) {

@wescleveland wescleveland Apr 13, 2016

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Can you add a console.log here that looks like [CACHE] HIT: ETAG MATCH ON url

response.status(304).end();
return true;
}

response.header('Cache-Control', 'private, no-cache');

@wescleveland wescleveland Apr 13, 2016

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There are a few spots in poseidon where we set private, no-cache, no-store, must-revalidate (doing a search for no-cache in dh2o-poseidon/src shows 4 files and a no_cache middleware that is applied to the entire app. Do any of these need to be changed?

I guess this line will correct that header if poseidon has set it to something else so maybe it doesn't matter.

response.header('ETag', contentHash);
response.send(value);
return true;
} else {
Expand All @@ -43,7 +57,8 @@ module.exports=function(invalidateTimeInMilliseconds,parameters){
console.log("[CACHE] RESPONSE CODE WAS "+this.statusCode+", NOT CACHING");
};
});
response.header('Cache-Control', 'private, no-cache, no-store, must-revalidate')
response.header('Cache-Control', 'private, no-cache');
response.header('ETag', getHash(chunk));
response.end(chunk, encoding);
};
return next();
Expand Down