1 hash
- Hash is a series of encryption algorithms. Although different hash algorithms have different encryption strengths, they have the following common points:
① No matter how large the amount of input data is, input the same hash algorithm to get the length of the encryption result fixed.
②The hash algorithm is determined, the input data is determined, and the output data can be guaranteed to be unchanged.
③The hash algorithm is determined, if the input data changes, the output data must change, and usually changes greatly.
④The hash algorithm is irreversible. The
underlying Git uses SHA- 1 Algorithm.
Hash algorithms can be used to verify files. The principle is shown in the figure below:
Git relies on this mechanism to fundamentally ensure data integrity.
2 Git save version mechanism
2.1 File management mechanism of centralized version control tools
Store information in the form of a file change list. Such systems view the information they save as a set of basic files and the cumulative differences of each file over time.
2.2 Git's file management mechanism
Git treats data as a set of snapshots of a small file system. Every time an update is submitted, Git will make a snapshot of all current files and save the index of this snapshot. For efficiency, if the file is not modified, Git will not re-store the file, but only keep a link to the previously stored file. So the way Git works can be called a snapshot stream.
2.3 Git file management mechanism details
- Git's "submit object"
- The chain formed by the submitted object and its parent object
3 Git branch management mechanism
3.1 Branch creation
3.2 Switching of branches
