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This article focuses on "Netty distributed methods to get objects from the recycler object Recycle Bin". Interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn "Netty distributed method of getting objects from the recycler object Recycle Bin".

Get the object from the object Recycle Bin get the object public static void main (String [] args) {User user1= RECYCLER.get (); user1.recycle (); User user2 = RECYCLER.get (); user2.recycle (); System.out.println (user1==user2);}

This gets the object through the get method of Recycler, which we follow in the get method:

Public final T get () {if (maxCapacityPerThread = = 0) {return newObject ((Handle) NOOP_HANDLE);} Stack stack = threadLocal.get (); DefaultHandle handle = stack.pop (); if (handle = = null) {handle = stack.newHandle (); handle.value = newObject (handle);} return (T) handle.value;}

First of all, determine whether maxCapacityPerThread is 0. MaxCapacityPerThread represents the maximum number of objects that stack can cache. If 0 objects are cached, none of the objects will be reclaimed.

This creates an object by calling newObject and passes in a NOOP_HANDLE. NOOP_HANDLE is a handle. Let's look at its definition:

Private static final Handle NOOP_HANDLE = new Handle () {@ Override public void recycle (Object object) {}}

The recycle method here is an empty implementation, which represents no object collection.

Go back to the get method

Let's look at the second step.

Stack stack = threadLocal.get ()

Here, the stack of the current thread is obtained through the FastThreadLocal object. The logic of getting the object by FastThreadLocal has been analyzed in the previous section, so I won't repeat it here.

After you get the stack, pop a handle from the stack, and we'll analyze this handle later.

If the object extracted is null, it means that there are no objects in the Recycle Bin. Usually, if the object is not recycled here for the first time, it will be null. In this way, a handle will be created through stack.newHandle ().

The value property of the created handle is assigned through our rewritten newObject method, that is, the user in our demo

We follow up the newHandle method DefaultHandle newHandle () {return new DefaultHandle (this);}

Here you create a DefaultHandle object and pass in this, where this is the current stack

Follow in the constructor of DefaultHandle:

DefaultHandle (Stack stack) {this.stack = stack;}

The stack property is initialized here

There is also a member variable of value in DefaultHandle

Private Object value

The value here is used to bind the recycled object itself.

Go back to the get method:

Analyzing handle, let's go back to the previous step:

DefaultHandle handle = stack.pop ()

We analyze the logic of popping up a handle from stack

Follow DefaultHandle pop () {int size = this.size; if (size = = 0) {if (! scavenge ()) {return null;} size = this.size;} size -; DefaultHandle ret = elements [size] in the pop method; elements [size] = null; if (ret.lastRecycledId! = ret.recycleId) {throw new IllegalStateException ("recycled multiple times") } ret.recycleId = 0; ret.lastRecycledId = 0; this.size = size; return ret;}

First get the size. Size represents the number of objects in the current stack.

If size is 0, the scavenge method is called, which is a method for recycling objects from different threads, which we will analyze in a later section

If the size is greater than zero, the size subtracts itself, which means that an element is taken out

Then take out the handle through the array subscript of size

Then set the current subscript to null

Finally, the attributes recycleId, lastRecycledId and size are assigned

We will analyze recycleId and lastRecycledId in a later section.

Go back to the get method:

Public final T get () {if (maxCapacityPerThread = = 0) {return newObject ((Handle) NOOP_HANDLE);} Stack stack = threadLocal.get (); DefaultHandle handle = stack.pop (); if (handle = = null) {handle = stack.newHandle (); handle.value = newObject (handle);} return (T) handle.value;}

Whether it is the handle popped up from the stack or the handle created, we have to get the object we actually use through handle.value.

At this point, I believe you have a deeper understanding of "Netty distributed method of getting objects from the recycler object Recycle Bin". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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