sqlite源码剖析(2)

声明：本SQLite源码剖析系列为刘兴(http://deepfuture.iteye.com/)原创，未经笔者授权，任何人和机构不能转载

/*

** The maximum number of opcodes in a VDBE program.

** Not currently enforced.

*/

//VDBE程序的最大操作码数目

#ifndef SQLITE_MAX_VDBE_OP

# define SQLITE_MAX_VDBE_OP 25000

#endif

 

/*

** The maximum number of arguments to an SQL function.

*/

//SQL函数的最大参数数目

#ifndef SQLITE_MAX_FUNCTION_ARG

# define SQLITE_MAX_FUNCTION_ARG 127

#endif

 

/*

** The maximum number of in-memory pages to use for the main database

** table and for temporary tables.  The SQLITE_DEFAULT_CACHE_SIZE

*/

//主数据库表和临时表的最大内存大小

#ifndef SQLITE_DEFAULT_CACHE_SIZE

# define SQLITE_DEFAULT_CACHE_SIZE  2000

#endif

#ifndef SQLITE_DEFAULT_TEMP_CACHE_SIZE

# define SQLITE_DEFAULT_TEMP_CACHE_SIZE  500

#endif

 

/*

** The maximum number of attached databases.  This must be between 0

** and 30.  The upper bound on 30 is because a 32-bit integer bitmap

** is used internally to track attached databases.

*/

//附加数据库的数目

#ifndef SQLITE_MAX_ATTACHED

# define SQLITE_MAX_ATTACHED 10

#endif

 

 

/*

** The maximum value of a ?nnn wildcard that the parser will accept.

*/

//解析器接受的匹配符参数最大值

#ifndef SQLITE_MAX_VARIABLE_NUMBER

# define SQLITE_MAX_VARIABLE_NUMBER 999

#endif

 

/* Maximum page size.  The upper bound on this value is 32768.  This a limit

** imposed by the necessity of storing the value in a 2-byte unsigned integer

** and the fact that the page size must be a power of 2.

**

** If this limit is changed, then the compiled library is technically

** incompatible with an SQLite library compiled with a different limit. If

** a process operating on a database with a page-size of 65536 bytes

** crashes, then an instance of SQLite compiled with the default page-size

** limit will not be able to rollback the aborted transaction. This could

** lead to database corruption.

*/

//最大页面大小

#ifndef SQLITE_MAX_PAGE_SIZE

# define SQLITE_MAX_PAGE_SIZE 32768

#endif

 

 

/*

** The default size of a database page.

*/

//数据库页面的默认大小

#ifndef SQLITE_DEFAULT_PAGE_SIZE

# define SQLITE_DEFAULT_PAGE_SIZE 1024

#endif

#if SQLITE_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE

# undef SQLITE_DEFAULT_PAGE_SIZE

# define SQLITE_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE

#endif

 

/*

** Ordinarily, if no value is explicitly provided, SQLite creates databases

** with page size SQLITE_DEFAULT_PAGE_SIZE. However, based on certain

** device characteristics (sector-size and atomic write() support),

** SQLite may choose a larger value. This constant is the maximum value

** SQLite will choose on its own.

*/

//数据库页面的最大默认大小

#ifndef SQLITE_MAX_DEFAULT_PAGE_SIZE

# define SQLITE_MAX_DEFAULT_PAGE_SIZE 8192

#endif

#if SQLITE_MAX_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE

# undef SQLITE_MAX_DEFAULT_PAGE_SIZE

# define SQLITE_MAX_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE

#endif

 

 

/*

** Maximum number of pages in one database file.

**

** This is really just the default value for the max_page_count pragma.

** This value can be lowered (or raised) at run-time using that the

** max_page_count macro.

*/

//单个数据库文件的最大页数数

#ifndef SQLITE_MAX_PAGE_COUNT

# define SQLITE_MAX_PAGE_COUNT 1073741823

#endif

 

/*

** Maximum length (in bytes) of the pattern in a LIKE or GLOB

** operator.

*/

// LIKE or GLOB模式的最大长度（字节）

#ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH

# define SQLITE_MAX_LIKE_PATTERN_LENGTH 50000

#endif

 

/*

** Maximum depth of recursion for triggers.

**

** A value of 1 means that a trigger program will not be able to itself

** fire any triggers. A value of 0 means that no trigger programs at all

** may be executed.

*/

//触发器程序的递归深度

#ifndef SQLITE_MAX_TRIGGER_DEPTH

# define SQLITE_MAX_TRIGGER_DEPTH 1000

#endif

//SQLITE限制参数定义完毕

/************** End of sqliteLimit.h *****************************************/

/************** Continuing where we left off in sqliteInt.h ******************/

//禁止Borland编译器的讨厌的警告

/* Disable nuisance warnings on Borland compilers */

#if defined(__BORLANDC__)

#pragma warn -rch /* unreachable code */

#pragma warn -ccc /* Condition is always true or false */

#pragma warn -aus /* Assigned value is never used */

#pragma warn -csu /* Comparing signed and unsigned */

#pragma warn -spa /* Suspicious pointer arithmetic */

#endif

//定义为GNU源码

/* Needed for various definitions... */

#ifndef _GNU_SOURCE

# define _GNU_SOURCE

#endif

 

/*

** Include standard header files as necessary

*/

//包含必要的头文件

#ifdef HAVE_STDINT_H

#include <stdint.h>

#endif

#ifdef HAVE_INTTYPES_H

#include <inttypes.h>

#endif

 

/*

** The number of samples of an index that SQLite takes in order to

** construct a histogram of the table content when running ANALYZE

** and with SQLITE_ENABLE_STAT2

*/

//索引样本数

#define SQLITE_INDEX_SAMPLES 10

 

/*

** The following macros are used to cast pointers to integers and

** integers to pointers.  The way you do this varies from one compiler

** to the next, so we have developed the following set of #if statements

** to generate appropriate macros for a wide range of compilers.

**

** The correct "ANSI" way to do this is to use the intptr_t type.

** Unfortunately, that typedef is not available on all compilers, or

** if it is available, it requires an #include of specific headers

** that very from one machine to the next.

**

** Ticket #3860:  The llvm-gcc-4.2 compiler from Apple chokes on

** the ((void*)&((char*)0)[X]) construct.  But MSVC chokes on ((void*)(X)).

** So we have to define the macros in different ways depending on the

** compiler.

*/

//下列宏完成指针转整数和整数转指针

#if defined(__PTRDIFF_TYPE__)  /* This case should work for GCC */

# define SQLITE_INT_TO_PTR(X)  ((void*)(__PTRDIFF_TYPE__)(X))

# define SQLITE_PTR_TO_INT(X)  ((int)(__PTRDIFF_TYPE__)(X))

#elif !defined(__GNUC__)       /* Works for compilers other than LLVM */

# define SQLITE_INT_TO_PTR(X)  ((void*)&((char*)0)[X])

# define SQLITE_PTR_TO_INT(X)  ((int)(((char*)X)-(char*)0))

#elif defined(HAVE_STDINT_H)   /* Use this case if we have ANSI headers */

# define SQLITE_INT_TO_PTR(X)  ((void*)(intptr_t)(X))

# define SQLITE_PTR_TO_INT(X)  ((int)(intptr_t)(X))

#else                          /* Generates a warning - but it always works */

# define SQLITE_INT_TO_PTR(X)  ((void*)(X))

# define SQLITE_PTR_TO_INT(X)  ((int)(X))

#endif

 

/*

** The SQLITE_THREADSAFE macro must be defined as either 0 or 1.

** Older versions of SQLite used an optional THREADSAFE macro.

** We support that for legacy

*/

// SQLITE_THREADSAFE线程安全宏被定义为0或1,

#if !defined(SQLITE_THREADSAFE)

#if defined(THREADSAFE)

# define SQLITE_THREADSAFE THREADSAFE

#else

# define SQLITE_THREADSAFE 1

#endif

#endif

 

/*

** The SQLITE_DEFAULT_MEMSTATUS macro must be defined as either 0 or 1.

** It determines whether or not the features related to

** SQLITE_CONFIG_MEMSTATUS are available by default or not. This value can

** be overridden at runtime using the sqlite3_config() API.

*/

// SQLITE_DEFAULT_MEMSTATUS宏被定义为0或1，在运行时可使

//用sqlite3_config() API修改该值

#if !defined(SQLITE_DEFAULT_MEMSTATUS)

# define SQLITE_DEFAULT_MEMSTATUS 1

#endif