How to remove groups of entries

I look into the test project, How can I get all the keys?

[Tratcher]

That's not supported in the current design.

Btw how to solved if i want to delete all the keys that start with "SOMEKEY.*"?

In the current .net 4 memoryobject usually i get allthekey then check the regex then remove the key.

[Tratcher]

I recommend using shared cache triggers or cache entry links to remove groups of items.

Triggers: Create a trigger and assign it to each item in the group. Fire the trigger when you want to remove all the items.
https://github.com/aspnet/Caching/blob/dev/samples/MemoryCacheSample/Program.cs#L90

Entry links: Create one item that is the root item. Use EntryLink's to make all other items depend on that one. When you want to remove all the items just remove the root item and the rest will be removed automatically.
https://github.com/aspnet/Caching/blob/dev/samples/MemoryCacheSample/Program.cs#L96

most of the time people store the key is in this format.
ex:

Keys:
[product].[tablename].{whatever}
membersite.language.all
membersite.language.id-{0}
membersite.language.iso-{0}
membersite.language.index-{0}.pagesize-{1}

When we want to perform CRUD operation
READ
//Most of the time we set the key

CREATE, UPDATE, DELETE
//Remove all the keys that startwith membersite.language.

Q1. Can you explain how that the pattern using trigger & entry links for above case.
Q2. Why we do not expose all the keys?

[Tratcher]

A2: The cache is considered highly unstable where entries could expire or be removed at any time. This would make simple code like the following unreliable.

foreach (var key in cache.Keys)
{
  var value = cache.Get(key);
  // ...
}

A1:

Bulk remove with shared expiration triggers:

// Remove on trigger
var cts = new CancellationTokenSource();
var sharedTrigger = new CancellationTokenTrigger(cts.Token);
cache.Set("key.a", context =>
{
  context.AddExpirationTrigger(sharedTrigger);
  return "value a";
});
cache.Set("key.b", context =>
{
  context.AddExpirationTrigger(sharedTrigger);
  return "value b";
});
// ...
// Remove all entries
cts.Cancel();

Bulk remove with EntryLinks:

cache.Set("Parent Key", "Parent Value");
var link = new EntryLink();
var parentValue = cache.Get("Parent Key", link);
result = cache.Set("Dependent Key", context =>
{
  context.AddEntryLink(link);
  return "Dependent Value";
});
// ...
cache.Remove("Parent Key"); // Also removes linked "Dependent Key"

Remove on Trigger - Is work fine to delete all keys.

I got error on EntryLinks

        var cache = new MemoryCache(new MemoryCacheOptions() {
            ListenForMemoryPressure = false
        });

        cache.Set("membersite.language.", "Language Pattern");
        var link = new EntryLink();
        var parentValue = cache.Get("membersite.language.", link);
        Assert.Equal("Language Pattern", parentValue);
        var result = cache.Set("membersite.language.id-1", context =>
        {
            context.AddEntryLink(link);
            return "en-US";
        });

        cache.Set("membersite.currency.", "Currency Pattern");
        link = new EntryLink();
        parentValue = cache.Get("membersite.currency.", link);
        Assert.Equal("Currency Pattern", parentValue);
        result = cache.Set("membersite.currency.id-1", context => {
            context.AddEntryLink(link);
            return "RMB";
        });

        var currency = cache.Get<string>("membersite.currency.id-1");
        Assert.Equal("RMB", currency);

        var language = cache.Get<string>("membersite.language.id-1");
        Assert.Equal("en-US", language);

        //Remove all the key start with membersite.currency.
        cache.Remove("membersite.language.");

        parentValue = cache.Get<string>("membersite.language.");
        Assert.Null(parentValue);

        language = cache.Get<string>("membersite.language.id-1");
        Console.WriteLine("Language: " + language);
        //How come the dependent key still there?
        Assert.Null(language);

        currency = cache.Get<string>("membersite.currency.id-1");
        Assert.Equal("RMB",currency);

From k test result
Membersite.Core.Tests.CacheTest.CacheEntryLink [FAIL]
Assert.Null() Failure
Expected: (null)
Actual: en-US

[Tratcher]

@Praburaj Can you run this and see what I did wrong?

[Praburaj]

@Tratcher I'll give it a try.

@Tratcher @Praburaj any updated on this one?

[Tratcher]

Ok, now I remember how entry links work. They don't create a direct link between keys, they instead copy any existing expiration information (triggers or timers) from the parent key to any sub keys.

            // Remove on trigger
            var cts = new CancellationTokenSource();
            result = cache.GetOrSet("Parent Key", state, context =>
            {
                context.AddExpirationTrigger(new CancellationTokenTrigger(cts.Token));
                return "Parent Value";
            });

            result = cache.Set("Dependent Key", context =>
            {
                // Share the CancellationTokenTrigger via EntryLink
                var link = new EntryLink();
                var parentValue = cache.Get("Parent Key", link);
                context.AddEntryLink(link);
                return "Dependent Value" + parentValue;
            });
            // ...
            Console.WriteLine(cache.Get("Dependent Key"));
            cts.Cancel(); // Also removes linked "Dependent Key"
            Console.WriteLine(cache.Get("Dependent Key"));

@Tratcher are you able to change the example test that i write?
cause the example of your code it hard to figure it out.

Appreciate your help

[Tratcher]

            var cache = new MemoryCache(new MemoryCacheOptions()
            {
                ListenForMemoryPressure = false
            });

            var langCts = new CancellationTokenSource();
            cache.Set("membersite.language.", ctx =>
            {
                ctx.AddExpirationTrigger(new CancellationTokenTrigger(langCts.Token));
                return "Language Pattern";
            });

            var link = new EntryLink();
            // Get all of the expiration triggers from the parent key
            var parentValue = cache.Get("membersite.language.", link);
            Assert.Equal("Language Pattern", parentValue);
            var result = cache.Set("membersite.language.id-1", context =>
            {
                // Copy the expiration triggers to this entry
                context.AddEntryLink(link);
                return "en-US";
            });

            var curCts = new CancellationTokenSource();
            cache.Set("membersite.currency.", ctx =>
            {
                ctx.AddExpirationTrigger(new CancellationTokenTrigger(curCts.Token));
                return "Currency Pattern";
            });
            link = new EntryLink();
            parentValue = cache.Get("membersite.currency.", link);
            Assert.Equal("Currency Pattern", parentValue);
            result = cache.Set("membersite.currency.id-1", context => {
                context.AddEntryLink(link);
                return "RMB";
            });

            var currency = cache.Get<string>("membersite.currency.id-1");
            Assert.Equal("RMB", currency);

            var language = cache.Get<string>("membersite.language.id-1");
            Assert.Equal("en-US", language);

            // Remove just the root key
            cache.Remove("membersite.language.");

            parentValue = cache.Get<string>("membersite.language.");
            Assert.Null(parentValue);

            language = cache.Get<string>("membersite.language.id-1");
            Assert.Equal("en-US", language);

            // Remove all the associated lang keys.
            langCts.Cancel();

            language = cache.Get<string>("membersite.language.id-1");
            Console.WriteLine("Language: " + language);
            Assert.Null(language);

            currency = cache.Get<string>("membersite.currency.id-1");
            Assert.Equal("RMB", currency);