开源软件名称：

sqlite

开源软件地址：

https://gitee.com/mirrors/sqlite

开源软件介绍：

SQLite Source Repository

This repository contains the complete source code for theSQLite database engine. Some test scriptsare also included. However, many other test scriptsand most of the documentation are managed separately.

Version Control

SQLite sources are managed using theFossil, a distributed version control systemthat was specifically designed and written to support SQLite development.The Fossil repository contains the urtext.

If you are reading this on GitHub or some other Git repository or service,then you are looking at a mirror. The names of check-ins andother artifacts in a Git mirror are different from the officialnames for those objects. The offical names for check-ins arefound in a footer on the check-in comment for authorized mirrors.The official check-in name can also be seen in the manifest.uuid filein the root of the tree. Always use the official name, not theGit-name, when communicating about an SQLite check-in.

If you pulled your SQLite source code from a secondary source and want toverify its integrity, there are hints on how to do that in theVerifying Code Authenticity section below.

Obtaining The Code

If you do not want to use Fossil, you can download tarballs or ZIParchives or SQLite archives as follows:

Lastest trunk check-in asTarball,ZIP-archive, orSQLite-archive.
Latest release asTarball,ZIP-archive, orSQLite-archive.
For other check-ins, substitute an appropriate branch name ortag or hash prefix in place of "release" in the URLs of the previousbullet. Or browse the timelineto locate the check-in desired, click on its information page link,then click on the "Tarball" or "ZIP Archive" links on the informationpage.

If you do want to use Fossil to check out the source tree,first install Fossil version 2.0 or later.(Source tarballs and precompiled binaries availablehere. Fossil isa stand-alone program. To install, simply download or build the singleexecutable file and put that file someplace on your $PATH.)Then run commands like this:

    mkdir -p ~/sqlite ~/Fossils    cd ~/sqlite    fossil clone https://www.sqlite.org/src ~/Fossils/sqlite.fossil    fossil open ~/Fossils/sqlite.fossil

After setting up a repository using the steps above, you can alwaysupdate to the lastest version using:

    fossil update trunk   ;# latest trunk check-in    fossil update release ;# latest official release

Or type "fossil ui" to get a web-based user interface.

Compiling for Unix-like systems

First create a directory in which to placethe build products. It is recommended, but not required, that thebuild directory be separate from the source directory. Cd into thebuild directory and then from the build directory run the configurescript found at the root of the source tree. Then run "make".

For example:

    tar xzf sqlite.tar.gz    ;#  Unpack the source tree into "sqlite"    mkdir bld                ;#  Build will occur in a sibling directory    cd bld                   ;#  Change to the build directory    ../sqlite/configure      ;#  Run the configure script    make                     ;#  Run the makefile.    make sqlite3.c           ;#  Build the "amalgamation" source file    make test                ;#  Run some tests (requires Tcl)

See the makefile for additional targets.

The configure script uses autoconf 2.61 and libtool. If the configurescript does not work out for you, there is a generic makefile named"Makefile.linux-gcc" in the top directory of the source tree that youcan copy and edit to suit your needs. Comments on the generic makefileshow what changes are needed.

Using MSVC for Windows systems

On Windows, all applicable build products can be compiled with MSVC.First open the command prompt window associated with the desired compilerversion (e.g. "Developer Command Prompt for VS2013"). Next, use NMAKEwith the provided "Makefile.msc" to build one of the supported targets.

For example, from the parent directory of the source subtree named "sqlite":

    mkdir bld    cd bld    nmake /f ..\sqlite\Makefile.msc TOP=..\sqlite    nmake /f ..\sqlite\Makefile.msc sqlite3.c TOP=..\sqlite    nmake /f ..\sqlite\Makefile.msc sqlite3.dll TOP=..\sqlite    nmake /f ..\sqlite\Makefile.msc sqlite3.exe TOP=..\sqlite    nmake /f ..\sqlite\Makefile.msc test TOP=..\sqlite

There are several build options that can be set via the NMAKE commandline. For example, to build for WinRT, simply add "FOR_WINRT=1" argumentto the "sqlite3.dll" command line above. When debugging into the SQLitecode, adding the "DEBUG=1" argument to one of the above command lines isrecommended.

SQLite does not require Tcl to run, but a Tcl installationis required by the makefiles (including those for MSVC). SQLite containsa lot of generated code and Tcl is used to do much of that code generation.

Source Code Tour

Most of the core source files are in the src/ subdirectory. Thesrc/ folder also contains files used to build the "testfixture" testharness. The names of the source files used by "testfixture" all beginwith "test".The src/ also contains the "shell.c" filewhich is the main program for the "sqlite3.exe"command-line shell andthe "tclsqlite.c" file which implements theTcl bindings for SQLite.(Historical note: SQLite began as a Tclextension and only later escaped to the wild as an independent library.)

Test scripts and programs are found in the test/ subdirectory.Addtional test code is found in other source repositories.See How SQLite Is Tested foradditional information.

The ext/ subdirectory contains code for extensions. TheFull-text search engine is in ext/fts3. The R-Tree engine is inext/rtree. The ext/misc subdirectory contains a number ofsmaller, single-file extensions, such as a REGEXP operator.

The tool/ subdirectory contains various scripts and programs usedfor building generated source code files or for testing or for generatingaccessory programs such as "sqlite3_analyzer(.exe)".

Generated Source Code Files

Several of the C-language source files used by SQLite are generated fromother sources rather than being typed in manually by a programmer. Thissection will summarize those automatically-generated files. To create allof the automatically-generated files, simply run "make target_source".The "target_source" make target will create a subdirectory "tsrc/" andfill it with all the source files needed to build SQLite, bothmanually-edited files and automatically-generated files.

The SQLite interface is defined by the sqlite3.h header file, which isgenerated from src/sqlite.h.in, ./manifest.uuid, and ./VERSION. TheTcl script at tool/mksqlite3h.tcl does the conversion.The manifest.uuid file contains the SHA3 hash of the particular check-inand is used to generate the SQLITE_SOURCE_ID macro. The VERSION filecontains the current SQLite version number. The sqlite3.h header is reallyjust a copy of src/sqlite.h.in with the source-id and version number insertedat just the right spots. Note that comment text in the sqlite3.h file isused to generate much of the SQLite API documentation. The Tcl scriptsused to generate that documentation are in a separate source repository.

The SQL language parser is parse.c which is generate from a grammar inthe src/parse.y file. The conversion of "parse.y" into "parse.c" is doneby the lemon LALR(1) parser generator. The source codefor lemon is at tool/lemon.c. Lemon uses the tool/lempar.c file as atemplate for generating its parser.Lemon also generates the parse.h header file, at the same time itgenerates parse.c.

The opcodes.h header file contains macros that define the numberscorresponding to opcodes in the "VDBE" virtual machine. The opcodes.hfile is generated by the scanning the src/vdbe.c source file. TheTcl script at ./mkopcodeh.tcl does this scan and generates opcodes.h.A second Tcl script, ./mkopcodec.tcl, then scans opcodes.h to generatethe opcodes.c source file, which contains a reverse mapping fromopcode-number to opcode-name that is used for EXPLAIN output.

The keywordhash.h header file contains the definition of a hash tablethat maps SQL language keywords (ex: "CREATE", "SELECT", "INDEX", etc.) intothe numeric codes used by the parse.c parser. The keywordhash.h file isgenerated by a C-language program at tool mkkeywordhash.c.

The pragma.h header file contains various definitions used to parseand implement the PRAGMA statements. The header is generated by ascript tool/mkpragmatab.tcl. If you want to add a new PRAGMA, editthe tool/mkpragmatab.tcl file to insert the information needed by theparser for your new PRAGMA, then run the script to regenerate thepragma.h header file.

The Amalgamation

All of the individual C source code and header files (both manually-editedand automatically-generated) can be combined into a single big source filesqlite3.c called "the amalgamation". The amalgamation is the recommendedway of using SQLite in a larger application. Combining all individualsource code files into a single big source code file allows the C compilerto perform more cross-procedure analysis and generate better code. SQLiteruns about 5% faster when compiled from the amalgamation versus when compiledfrom individual source files.

The amalgamation is generated from the tool/mksqlite3c.tcl Tcl script.First, all of the individual source files must be gathered into the tsrc/subdirectory (using the equivalent of "make target_source") then thetool/mksqlite3c.tcl script is run to copy them all together in just theright order while resolving internal "#include" references.

The amalgamation source file is more than 200K lines long. Some symbolicdebuggers (most notably MSVC) are unable to deal with files longer than 64Klines. To work around this, a separate Tcl script, tool/split-sqlite3c.tcl,can be run on the amalgamation to break it up into a single small C filecalled sqlite3-all.c that does #include on about seven other filesnamed sqlite3-1.c, sqlite3-2.c, ..., sqlite3-7.c. In this way,all of the source code is contained within a single translation unit sothat the compiler can do extra cross-procedure optimization, but noindividual source file exceeds 32K lines in length.

How It All Fits Together

SQLite is modular in design.See the architectural descriptionfor details. Other documents that are useful in(helping to understand how SQLite works include thefile format description,the virtual machine that runsprepared statements, the description ofhow transactions work, andthe overview of the query planner.

Years of effort have gone into optimizating SQLite, bothfor small size and high performance. And optimizations tend to result incomplex code. So there is a lot of complexity in the current SQLiteimplementation. It will not be the easiest library in the world to hack.

Key files:

sqlite.h.in - This file defines the public interface to the SQLitelibrary. Readers will need to be familiar with this interface beforetrying to understand how the library works internally.
sqliteInt.h - this header file defines many of the data objectsused internally by SQLite. In addition to "sqliteInt.h", somesubsystems have their own header files.
parse.y - This file describes the LALR(1) grammar that SQLite usesto parse SQL statements, and the actions that are taken at each stepin the parsing process.
vdbe.c - This file implements the virtual machine that runsprepared statements. There are various helper files whose namesbegin with "vdbe". The VDBE has access to the vdbeInt.h header filewhich defines internal data objects. The rest of SQLite interactswith the VDBE through an interface defined by vdbe.h.
where.c - This file (together with its helper files namedby "where*.c") analyzes the WHERE clause and generatesvirtual machine code to run queries efficiently. This file issometimes called the "query optimizer". It has its own privateheader file, whereInt.h, that defines data objects used internally.
btree.c - This file contains the implementation of the B-Treestorage engine used by SQLite. The interface to the rest of the systemis defined by "btree.h". The "btreeInt.h" header defines objectsused internally by btree.c and not published to the rest of the system.
pager.c - This file contains the "pager" implementation, themodule that implements transactions. The "pager.h" header filedefines the interface between pager.c and the rest of the system.
os_unix.c and os_win.c - These two files implement the interfacebetween SQLite and the underlying operating system using the run-timepluggable VFS interface.
shell.c.in - This file is not part of the core SQLite library. Thisis the file that, when linked against sqlite3.a, generates the"sqlite3.exe" command-line shell. The "shell.c.in" file is transformedinto "shell.c" as part of the build process.
tclsqlite.c - This file implements the Tcl bindings for SQLite. Itis not part of the core SQLite library. But as most of the tests in thisrepository are written in Tcl, the Tcl language bindings are important.
test.c* - Files in the src/ folder that begin with "test" go intobuilding the "testfixture.exe" program. The testfixture.exe program isan enhanced Tcl shell. The testfixture.exe program runs scripts in thetest/ folder to validate the core SQLite code. The testfixture program(and some other test programs too) is build and run when you type"make test".
ext/misc/json1.c - This file implements the various JSON functionsthat are build into SQLite.

There are many other source files. Each has a succinct header comment thatdescribes its purpose and role within the larger system.

Verifying Code Authenticity

The manifest file at the root directory of the source treecontains either a SHA3-256 hash (for newer files) or a SHA1 hash (forolder files) for every source file in the repository.The name of the version of the entire source tree is just theSHA3-256 hash of the manifest file itself, possibly with thelast line of that file omitted if the last line begins with"# Remove this line".The manifest.uuid file should contain the SHA3-256 hash of themanifest file. If all of the above hash comparisons are correct, thenyou can be confident that your source tree is authentic and unadulterated.

The format of the manifest file should be mostly self-explanatory, butif you want details, they are availablehere.