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add keepalive option #17

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add keepalive option #17

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21ea7a7
add "useStale" option.
tangxinfa Dec 5, 2016
af245b9
test "useStale" option.
tangxinfa Dec 9, 2016
c64a8f6
makesure staleCallback called.
tangxinfa Dec 12, 2016
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4 changes: 3 additions & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,8 @@ var dns = require('dns'),
dnscache = require('dnscache')({
"enable" : true,
"ttl" : 300,
"cachesize" : 1000
"cachesize" : 1000,
"useStale": false
});

//to use the cached dns either of dnscache or dns can be called.
Expand All @@ -52,6 +53,7 @@ Configuration
* `ttl` - ttl for cache-entries. Default: `300`
* `cachesize` - number of cache entries, defaults to `1000`
* `cache` - If a custom cache needs to be used instead of the supplied cache implementation. Only for Advanced Usage. Custom Cache needs to have same interface for `get` and `set`.
* `useStale` - When cache expires, user can be served stale value and re-fetched in the background, defaults to `false`.


Advanced Caching
Expand Down
18 changes: 13 additions & 5 deletions lib/cache.js
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,8 @@ var CacheObject = function (conf) {
conf = conf || {};
conf.ttl = parseInt(conf.ttl, 10) || 300; //0 is not permissible
conf.cachesize = parseInt(conf.cachesize, 10) || 1000; //0 is not permissible

conf.useStale = conf.useStale || false;

this.ttl = conf.ttl * 1000;
this.max = conf.cachesize;

Expand Down Expand Up @@ -36,15 +37,15 @@ var CacheObject = function (conf) {
}

self.head.val = value;
self.head.hit = 0;
self.head.ts = Date.now();
} else {
// key is not exist
self.data[key] = {
"key" : key,
"val" : value,
"hit" : 0,
"ts" : Date.now()
"ts" : Date.now(),
"stale": false
};

if (!self.head) {
Expand Down Expand Up @@ -84,7 +85,8 @@ var CacheObject = function (conf) {
}
next(function () {
var value;
if (conf.ttl !== 0 && (Date.now() - self.data[key].ts) >= self.ttl) {
var expired = conf.ttl !== 0 && (Date.now() - self.data[key].ts) >= self.ttl;
if (expired && !conf.useStale) {
if (self.data[key].newer) {
if (self.data[key].older) {
// in the middle of the list
Expand Down Expand Up @@ -113,7 +115,13 @@ var CacheObject = function (conf) {
self.data[key].hit = self.data[key].hit + 1;
value = self.data[key].val;
}
callback(null, value);

var staleCallback;
if (expired && conf.useStale && !self.data[key].stale) {
self.data[key].stale = true;
staleCallback = function () { self.data[key].stale = false; };
}
callback(null, value, staleCallback);
});
};
};
Expand Down
168 changes: 145 additions & 23 deletions lib/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@ var EnhanceDns = function (conf) {
conf = conf || {};
conf.ttl = parseInt(conf.ttl, 10) || 300; //0 is not allowed ie it ttl is set to 0, it will take the default
conf.cachesize = parseInt(conf.cachesize, 10); //0 is allowed but it will disable the caching
conf.useStale = conf.useStale || false;

if (isNaN(conf.cachesize)) {
conf.cachesize = 1000; //set default cache size to 1000 records max
Expand Down Expand Up @@ -71,13 +72,26 @@ var EnhanceDns = function (conf) {
}
}

cache.get('lookup_' + domain + '_' + family + '_' + hints + '_' + all, function (error, record) {
cache.get('lookup_' + domain + '_' + family + '_' + hints + '_' + all, function (error, record, staleCallback) {
if (record) {
/*istanbul ignore next - "all" option require node 4+*/
if (Array.isArray(record)) {
return callback(error, record);
/*istanbul ignore next - doesn't throw under normal circumstances*/
try {
/*istanbul ignore next - "all" option require node 4+*/
if (Array.isArray(record)) {
callback(error, record);
} else {
callback(error, record.address, record.family);
}
} catch (e) {
if (staleCallback) {
staleCallback();
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This seems to be saying "if an exception is thrown mark the cache entry as not stale", does that make sense?

}
throw e;
}
if (! staleCallback) {
return;
}
return callback(error, record.address, record.family);
callback = staleCallback;
}

try{
Expand Down Expand Up @@ -118,9 +132,21 @@ var EnhanceDns = function (conf) {
callback_new = type;
}

cache.get('resolve_' + domain + '_' + type_new, function (error, record) {
cache.get('resolve_' + domain + '_' + type_new, function (error, record, staleCallback) {
if (record) {
return callback_new(error, deepCopy(record), true);
/*istanbul ignore next - doesn't throw under normal circumstances*/
try {
callback_new(error, deepCopy(record), true);
} catch (e) {
if (staleCallback) {
staleCallback();
}
throw e;
}
if (! staleCallback) {
return;
}
callback_new = staleCallback;
}
try {
backup_object.resolve(domain, type_new, function (err, addresses) {
Expand All @@ -140,9 +166,21 @@ var EnhanceDns = function (conf) {

// override dns.resolve4 method
dns.resolve4 = function (domain, callback) {
cache.get('resolve4_' + domain, function (error, record) {
cache.get('resolve4_' + domain, function (error, record, staleCallback) {
if (record) {
return callback(error, deepCopy(record));
/*istanbul ignore next - doesn't throw under normal circumstances*/
try {
callback(error, deepCopy(record));
} catch (e) {
if (staleCallback) {
staleCallback();
}
throw e;
}
if (! staleCallback) {
return;
}
callback = staleCallback;
}
try {
backup_object.resolve4(domain, function (err, addresses) {
Expand All @@ -162,9 +200,21 @@ var EnhanceDns = function (conf) {

// override dns.resolve6 method
dns.resolve6 = function (domain, callback) {
cache.get('resolve6_' + domain, function (error, record) {
cache.get('resolve6_' + domain, function (error, record, staleCallback) {
if (record) {
return callback(error, deepCopy(record));
/*istanbul ignore next - doesn't throw under normal circumstances*/
try {
callback(error, deepCopy(record));
} catch (e) {
if (staleCallback) {
staleCallback();
}
throw e;
}
if (! staleCallback) {
return;
}
callback = staleCallback;
}
try {
backup_object.resolve6(domain, function (err, addresses) {
Expand All @@ -184,9 +234,21 @@ var EnhanceDns = function (conf) {

// override dns.resolveMx method
dns.resolveMx = function (domain, callback) {
cache.get('resolveMx_' + domain, function (error, record) {
cache.get('resolveMx_' + domain, function (error, record, staleCallback) {
if (record) {
return callback(error, deepCopy(record));
/*istanbul ignore next - doesn't throw under normal circumstances*/
try {
callback(error, deepCopy(record));
} catch (e) {
if (staleCallback) {
staleCallback();
}
throw e;
}
if (! staleCallback) {
return;
}
callback = staleCallback;
}
try {
backup_object.resolveMx(domain, function (err, addresses) {
Expand All @@ -206,9 +268,21 @@ var EnhanceDns = function (conf) {

// override dns.resolveTxt method
dns.resolveTxt = function (domain, callback) {
cache.get('resolveTxt_' + domain, function (error, record) {
cache.get('resolveTxt_' + domain, function (error, record, staleCallback) {
if (record) {
return callback(error, deepCopy(record));
/*istanbul ignore next - doesn't throw under normal circumstances*/
try {
callback(error, deepCopy(record));
} catch (e) {
if (staleCallback) {
staleCallback();
}
throw e;
}
if (! staleCallback) {
return;
}
callback = staleCallback;
}
try {
backup_object.resolveTxt(domain, function (err, addresses) {
Expand All @@ -228,9 +302,21 @@ var EnhanceDns = function (conf) {

// override dns.resolveSrv method
dns.resolveSrv = function (domain, callback) {
cache.get('resolveSrv_' + domain, function (error, record) {
cache.get('resolveSrv_' + domain, function (error, record, staleCallback) {
if (record) {
return callback(error, deepCopy(record));
/*istanbul ignore next - doesn't throw under normal circumstances*/
try {
callback(error, deepCopy(record));
} catch (e) {
if (staleCallback) {
staleCallback();
}
throw e;
}
if (! staleCallback) {
return;
}
callback = staleCallback;
}
try {
backup_object.resolveSrv(domain, function (err, addresses) {
Expand All @@ -250,9 +336,21 @@ var EnhanceDns = function (conf) {

// override dns.resolveNs method
dns.resolveNs = function (domain, callback) {
cache.get('resolveNs_' + domain, function (error, record) {
cache.get('resolveNs_' + domain, function (error, record, staleCallback) {
if (record) {
return callback(error, deepCopy(record));
/*istanbul ignore next - doesn't throw under normal circumstances*/
try {
callback(error, deepCopy(record));
} catch (e) {
if (staleCallback) {
staleCallback();
}
throw e;
}
if (! staleCallback) {
return;
}
callback = staleCallback;
}
try {
backup_object.resolveNs(domain, function (err, addresses) {
Expand All @@ -272,9 +370,21 @@ var EnhanceDns = function (conf) {

// override dns.resolveCname method
dns.resolveCname = function (domain, callback) {
cache.get('resolveCname_' + domain, function (error, record) {
cache.get('resolveCname_' + domain, function (error, record, staleCallback) {
if (record) {
return callback(error, deepCopy(record));
/*istanbul ignore next - doesn't throw under normal circumstances*/
try {
callback(error, deepCopy(record));
} catch (e) {
if (staleCallback) {
staleCallback();
}
throw e;
}
if (! staleCallback) {
return;
}
callback = staleCallback;
}
try {
backup_object.resolveCname(domain, function (err, addresses) {
Expand All @@ -294,9 +404,21 @@ var EnhanceDns = function (conf) {

// override dns.reverse method
dns.reverse = function (ip, callback) {
cache.get('reverse_' + ip, function (error, record) {
cache.get('reverse_' + ip, function (error, record, staleCallback) {
if (record) {
return callback(error, deepCopy(record));
/*istanbul ignore next - doesn't throw under normal circumstances*/
try {
callback(error, deepCopy(record));
} catch (e) {
if (staleCallback) {
staleCallback();
}
throw e;
}
if (! staleCallback) {
return;
}
callback = staleCallback;
}
try {
backup_object.reverse(ip, function (err, addresses) {
Expand Down
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