SDWeb (Image Cache Architecture Design)

SDWeb (Image Cache Architecture Design)

optimization

Reduce the amount of tasks

• No need after caching

Transfer tasks

• More sub-threading operations
• What did your task do
• What did the underlying system do

How to cancel an unloaded picture

How to remove duplicates when loading a picture at the same time

Loading process

First load

• Network operation (download)

  • Save local

    • Load picture

Second load

• Take local

bitmap

• A bitmap format for operations in threads

Class composition

Manager

• Multi-level caching strategy

  • RAM

  • Disk

  • Network download

    • time consuming
    • Flow loss

Find process

• Find start

  • Memory hit

    • YES

    • NO

      • Disk hit

        • YES

        • NO

          • Network download

            • End

important point

How to read and write pictures?

• Use the URL of the picture as the key
• Encrypt the URL of the picture after MD5 (safe)
• Use the one-way HASH value of the picture URL as the KEY (similar to 2)

Principles of computer organization

• Multi-level cache (improve search efficiency)
• Elimination algorithm (reasonable management space)

Architecture design

Memory design

• Storage Size

  • N small pictures
  • N photos
  • Big picture N

• Elimination strategy

  • Queue form

  • LRU

    • the way

      • Check trigger timing/frequency

        • Every time you read and write
        • When switching between front and back

      • Regular check

    • Disadvantage

      • space
      • time

Disk design

• characteristic

  • big space
  • Low reading efficiency

• design

  • Storage method
  • Size limit
  • Elimination strategy

Network design

• Maximum concurrent image request
• Request timeout policy (retry once)
• Request priority (task)

Picture decoding

• After disk read
• After the network request returns
• Decoding timing (to be displayed as a premise)
• Different formats of pictures adopt strategic mode to improve the stability of the frame

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