Example sharing of PHP using APC module to implement upload progress bar

This article mainly introduces how PHP uses the APC module to implement the file upload progress bar, analyzes the specific usage of the APC module, and gives APC related configuration instructions. I hope to be helpful.

Previous versions before php5.2 could not use the APC module, because there was no such APC module at all. If we want to use the APC module to implement the upload progress bar, we must be php5.2 or higher. Version.

Starting from 5.2, APC has added something called APC_UPLOAD_PROGRESS, which solves the progress bar problem that has been bothering everyone for a long time. And it changed the original method of caching all temporary files into the memory during uploading to automatically saving them to the hard disk when the temporary files reach the set value, which effectively improved the memory utilization.

It works by giving each upload a unique ID when uploading. When the PHP script receives an uploaded file, the interpreter will automatically check the hidden field named APC_UPLOAD_PROGRESS in the $_POST array. It Will become a cache variable that stores information about the upload so scripts can access status information about the uploaded file via the upload ID.

APC is the abbreviation of Alternative PHP Cache, which is a free and public optimized code cache for PHP. It is used to provide a free, open and robust framework for caching and optimizing PHP intermediate code.

Parameter configuration of APC module, the code is as follows:

Now that the configuration is complete, start writing the program

XML/HTML code is as follows:

The most important thing is the hidden field of APC_UPLOAD_PROGRESS. With it, the script can access the status of the currently uploaded file, and add a p to display the upload status. .

The following is a script for processing Ajax. I used the Jquery framework and json to transmit messages.

The JavaScript code is as follows:

The following is the PHP code for reading the upload status. As for the processing of uploaded files, you can write it as usual. The code is as follows:

Some detailed explanations about apc configuration :

apc.enabled Boolean

apc.enabled can be set to 0 to disable APC. This is mainly useful when APC is statically compiled into PHP, because there is no Other ways to disable it are to comment out the extension line in php.ini when compiling to DSO.

apc.shm_segments integer

Allocates shared memory blocks for the compilation cache Quantity, if APC runs out of shared memory and you have set apc.shm_size to the maximum value allowed by the system, you can try to increase the value of this parameter.

apc.shm_size integer

The size of each shared memory block is in MB. By default, some systems (including most BSD variants) have very low shared memory block size limits.

apc.optimization Integer

Optimization level. Set to 0 to disable optimization, higher values ​​use more powerful optimizations. Expect modest speed improvements. This is still experimental in nature.

apc.num_files_hint Integer

Hints on the number of different source files that are included and requested on your web server. If you are unsure, set it to 0 or omit it; this setting is likely to be useful primarily on sites with thousands of source files.

apc.ttl Integer

When a cache entry is needed by another entry in the cache area, what we need to consider is that the cache entry's location in the cache area is allowed to be free. Number of seconds. Setting this parameter to 0 means that your cache may be filled with stale entries, and new entries will not be cached.

apc.gc_ttl Integer

The number of seconds the cache entry survives in the garbage collection list. This value provides error protection in the event that a cached source file is executed and the server process dies at the same time. If that source file is modified, the memory allocated to the old version of the cache entry will not be reclaimed until the TTL value set by this parameter is reached. Setting it to 0 disables this feature.

apc.cache_by_default Boolean

Defaults to On, but can be set to Off and used in conjunction with apc.filters starting with a plus sign. Files will only be cached if they match the filter. .

apc.filters String

A comma-separated list of POSIX extended regular expressions. If any pattern matches the source file name, the file will not be cached. Note that the file name used to match is the file name passed to include/require, not the absolute path. If the first character of the regular expression is + , then the expression means that any file matching the expression will be cached, if the first character is - then any matches will not be cached. - is the default value, so can be omitted.

apc.mmap_file_mask string

apc.slam_defense integer

On a very busy server, whether you start a service or modify a file, you will cause a race for multiple processes to try to cache the same file at the same time. This option sets the percentage at which the process skips attempts to cache an uncached file. Or think of this as the probability of a single process skipping the cache. For example, setting apc.slam_defense to 75 means that the process has a 75% chance of not caching uncached files. Therefore, the higher the setting, the more likely it is to reduce the cache collision probability. Set to 0 to disable this feature.

apc.file_update_protection integer

When you modify a file on a running server, you should perform atomic operations. That is, write a temporary file first, and then rename (mv) the file to its final location when finished. Many text editors, cp, tar and some other similar programs do not operate this way. This means there is an opportunity to access and (cache) the file while the file is still being written. The setting of apc.file_update_protection causes the cache to delay marking new files. The default value is 2, which means that if the modification time of the file is found to be less than 2 seconds from the access time, the file will not be cached. Unlucky users who access a half-written file will see bizarre behavior, but at least it's not persistent. If you are sure that you frequently use atomic operations to update your files, you can turn off this protection by setting this parameter to 0. If your system is flooded with IO operations and causing the update process to take more than 2 seconds, you may need to increase this value.

apc.enable-cli integer

is mostly used for testing and debugging, to enable APC functionality for the CLI version of PHP. Generally speaking, you will not think of enabling APC for every CLI request. Create, port and discard APC's cache, but for various testing situations it is easy to enable APC for the CLI version.

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Sample code for using apc cache in php

Memcached PHP Memcached + APC + file cache encapsulation implementation code

PHP OPCode cache APC detailed introduction

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