tokyo cabinet源代码分析2
tokyo cabinet（以下简称TC）作为一个程序库，其中并没有main函数，那么我们该如何去开始代码阅读工作，这里的基本思路如下：
1. 首先明确TC中数据类型
2. 按照example的示例程序了解TC的运行过程。
TC中仅仅包含了8个头文件，各个头文件作用如下：
1. Md5.h 定义md5算法中需要使用的数据类型，和md5函数原型声明
2. Myconf.h 程序配置信息，通用头文件等
3. Tcadb.h 定义Abstract db类型，并声明相关操作函数
4. Tcbdb.h 定义B+ tree database类型，并声明相关操作函数
5. Tcfdb.h 定义fixed-length database类型，并声明相关操作函数
6. Tchdb.h 定义 Hash database类型，并声明相关操作函数
7. Tctdb.h 定义table database类型，并声明相关操作函数
8. Tcutil.h 定义tc中使用到的数据类型，例如TCLIST，TCXSTR等，并声明相关类型的操作函数。
1. 字符串TCXSTR
typedef struct { /* type of structure for an extensible string object */
char *ptr; /* pointer to the region */
int size; /* size of the region */
int asize; /* size of the allocated region */
} TCXSTR;
2. List类型 TCLIST
// Data type TCLIST
// arr1, arr2, arr3 .................. arrN
// [start ... start + num - 1 ]
typedef struct { /* type of structure for an array list */
TCLISTDATUM *array; /* array of data */
int anum; /* number of the elements of the array */
int start; /* start index of used elements */
int num; /* number of used elements */
} TCLIST;
pointer list：
typedef struct { /* type of structure for a pointer list */
void **array; /* array of pointers */
int anum; /* number of the elements of the array */
int start; /* start index of used elements */
int num; /* number of used elements */
} TCPTRLIST;
3. hashmap类型TCMAP
typedef struct _TCMAPREC { /* type of structure for an element of a map */
int32_t ksiz; /* size of the region of the key */
int32_t vsiz; /* size of the region of the value */
struct _TCMAPREC *left; /* pointer to the left child */
struct _TCMAPREC *right; /* pointer to the right child */
struct _TCMAPREC *prev; /* pointer to the previous element */
struct _TCMAPREC *next; /* pointer to the next element */
} TCMAPREC;
typedef struct { /* type of structure for a map */
TCMAPREC **buckets; /* bucket array */
TCMAPREC *first; /* pointer to the first element */
TCMAPREC *last; /* pointer to the last element */
TCMAPREC *cur; /* pointer to the current element */
uint32_t bnum; /* number of buckets */
uint64_t rnum; /* number of records */
uint64_t msiz; /* total size of records */
} TCMAP;4.ordered tree
typedef struct _TCTREEREC { /* type of structure for an element of a tree */
int32_t ksiz; /* size of the region of the key */
int32_t vsiz; /* size of the region of the value */
struct _TCTREEREC *left; /* pointer to the left child */
struct _TCTREEREC *right; /* pointer to the right child */
} TCTREEREC;
typedef struct { /* type of structure for a tree */
TCTREEREC *root; /* pointer to the root element */
TCTREEREC *cur; /* pointer to the current element */
uint64_t rnum; /* number of records */
uint64_t msiz; /* total size of records */
TCCMP cmp; /* pointer to the comparison function */
void *cmpop; /* opaque object for the comparison function */
} TCTREE;
5. on-memory hash database
typedef struct { /* type of structure for a on-memory hash database */
void **mmtxs; /* mutexes for method */
void *imtx; /* mutex for iterator */
TCMAP **maps; /* internal map objects */
int iter; /* index of maps for the iterator */
} TCMDB;
6.on-memory tree database
typedef struct { /* type of structure for a on-memory tree database */
void *mmtx; /* mutex for method */
TCTREE *tree; /* internal tree object */
} TCNDB;
7. 内存池
typedef struct { /* type of an element of memory pool */
void *ptr; /* pointer */
void (*del)(void *); /* deleting function */
} TCMPELEM;
typedef struct { /* type of structure for a memory pool object */
void *mutex; /* mutex for operations */
TCMPELEM *elems; /* array of elements */
int anum; /* number of the elements of the array */
int num; /* number of used elements */
} TCMPOOL;
8. 分布式一致哈希类型
typedef struct { /* type of structure for a consistent hashing node */
uint32_t seq; /* sequential number */
uint32_t hash; /* hash value */
} TCCHIDXNODE;
typedef struct { /* type of structure for a consistent hashing object */
TCCHIDXNODE *nodes; /* node array */
int nnum; /* number of the node array */
} TCCHIDX;
9. database类型：abstract database
// Abstract database
// TCADB = Tokyo Cabinet Abstract db
typedef struct { /* type of structure for an abstract database */
int omode; /* open mode */
TCMDB *mdb; /* on-memory hash database object */
TCNDB *ndb; /* on-memory tree database object */
TCHDB *hdb; /* hash database object */
TCBDB *bdb; /* B+ tree database object */
TCFDB *fdb; /* fixed-length databae object */
TCTDB *tdb; /* table database object */
int64_t capnum; /* capacity number of records */
int64_t capsiz; /* capacity size of using memory */
uint32_t capcnt; /* count for capacity check */
BDBCUR *cur; /* cursor of B+ tree */
void *skel; /* skeleton database */
} TCADB;
10. TCHDB
// TCHDB = Tokyo Cabinet Hash database
typedef struct { /* type of structure for a hash database */
void *mmtx; /* mutex for method */
void *rmtxs; /* mutexes for records */
void *dmtx; /* mutex for the while database */
void *wmtx; /* mutex for write ahead logging */
void *eckey; /* key for thread specific error code */
char *rpath; /* real path for locking */
uint8_t type; /* database type */
uint8_t flags; /* additional flags */
uint64_t bnum; /* number of the bucket array */
uint8_t apow; /* power of record alignment */
uint8_t fpow; /* power of free block pool number */
uint8_t opts; /* options */
char *path; /* path of the database file */
int fd; /* file descriptor of the database file */
uint32_t omode; /* open mode */
uint64_t rnum; /* number of the records */
uint64_t fsiz; /* size of the database file */
uint64_t frec; /* offset of the first record */
uint64_t dfcur; /* offset of the cursor for defragmentation */
uint64_t iter; /* offset of the iterator */
char *map; /* pointer to the mapped memory */
uint64_t msiz; /* size of the mapped memory */
uint64_t xmsiz; /* size of the extra mapped memory */
uint64_t xfsiz; /* extra size of the file for mapped memory */
uint32_t *ba32; /* 32-bit bucket array */
uint64_t *ba64; /* 64-bit bucket array */
uint32_t align; /* record alignment */
uint32_t runit; /* record reading unit */
bool zmode; /* whether compression is used */
int32_t fbpmax; /* maximum number of the free block pool */
void *fbpool; /* free block pool */
int32_t fbpnum; /* number of the free block pool */
int32_t fbpmis; /* number of missing retrieval of the free block pool */
bool async; /* whether asynchronous storing is called */
TCXSTR *drpool; /* delayed record pool */
TCXSTR *drpdef; /* deferred records of the delayed record pool */
uint64_t drpoff; /* offset of the delayed record pool */
TCMDB *recc; /* cache for records */
uint32_t rcnum; /* maximum number of cached records */
TCCODEC enc; /* pointer to the encoding function */
void *encop; /* opaque object for the encoding functions */
TCCODEC dec; /* pointer to the decoding function */
void *decop; /* opaque object for the decoding functions */
int ecode; /* last happened error code */
bool fatal; /* whether a fatal error occured */
uint64_t inode; /* inode number */
time_t mtime; /* modification time */
uint32_t dfunit; /* unit step number of auto defragmentation */
uint32_t dfcnt; /* counter of auto defragmentation */
bool tran; /* whether in the transaction */
int walfd; /* file descriptor of write ahead logging */
uint64_t walend; /* end offset of write ahead logging */
int dbgfd; /* file descriptor for debugging */
volatile int64_t cnt_writerec; /* tesing counter for record write times */
volatile int64_t cnt_reuserec; /* tesing counter for record reuse times */
volatile int64_t cnt_moverec; /* tesing counter for record move times */
volatile int64_t cnt_readrec; /* tesing counter for record read times */
volatile int64_t cnt_searchfbp; /* tesing counter for FBP search times */
volatile int64_t cnt_insertfbp; /* tesing counter for FBP insert times */
volatile int64_t cnt_splicefbp; /* tesing counter for FBP splice times */
volatile int64_t cnt_dividefbp; /* tesing counter for FBP divide times */
volatile int64_t cnt_mergefbp; /* tesing counter for FBP merge times */
volatile int64_t cnt_reducefbp; /* tesing counter for FBP reduce times */
volatile int64_t cnt_appenddrp; /* tesing counter for DRP append times */
volatile int64_t cnt_deferdrp; /* tesing counter for DRP defer times */
volatile int64_t cnt_flushdrp; /* tesing counter for DRP flush times */
volatile int64_t cnt_adjrecc; /* tesing counter for record cache adjust times */
volatile int64_t cnt_defrag; /* tesing counter for defragmentation times */
volatile int64_t cnt_shiftrec; /* tesing counter for record shift times */
volatile int64_t cnt_trunc; /* tesing counter for truncation times */
} TCHDB;
11. B+ tree database
// B+ tree database
// TCBDB = Tokyo Cabinet B+ database
typedef struct { /* type of structure for a B+ tree database */
void *mmtx; /* mutex for method */
void *cmtx; /* mutex for cache */
TCHDB *hdb; /* internal database object */
char *opaque; /* opaque buffer */
bool open; /* whether the internal database is opened */
bool wmode; /* whether to be writable */
uint32_t lmemb; /* number of members in each leaf */
uint32_t nmemb; /* number of members in each node */
uint8_t opts; /* options */
uint64_t root; /* ID number of the root page */
uint64_t first; /* ID number of the first leaf */
uint64_t last; /* ID number of the last leaf */
uint64_t lnum; /* number of leaves */
uint64_t nnum; /* number of nodes */
uint64_t rnum; /* number of records */
TCMAP *leafc; /* cache for leaves */
TCMAP *nodec; /* cache for nodes */
TCCMP cmp; /* pointer to the comparison function */
void *cmpop; /* opaque object for the comparison function */
uint32_t lcnum; /* maximum number of cached leaves */
uint32_t ncnum; /* maximum number of cached nodes */
uint32_t lsmax; /* maximum size of each leaf */
uint32_t lschk; /* counter for leaf size checking */
uint64_t capnum; /* capacity number of records */
uint64_t *hist; /* history array of visited nodes */
int hnum; /* number of element of the history array */
volatile uint64_t hleaf; /* ID number of the leaf referred by the history */
volatile uint64_t lleaf; /* ID number of the last visited leaf */
bool tran; /* whether in the transaction */
char *rbopaque; /* opaque for rollback */
volatile uint64_t clock; /* logical clock */
volatile int64_t cnt_saveleaf; /* tesing counter for leaf save times */
volatile int64_t cnt_loadleaf; /* tesing counter for leaf load times */
volatile int64_t cnt_killleaf; /* tesing counter for leaf kill times */
volatile int64_t cnt_adjleafc; /* tesing counter for node cache adjust times */
volatile int64_t cnt_savenode; /* tesing counter for node save times */
volatile int64_t cnt_loadnode; /* tesing counter for node load times */
volatile int64_t cnt_adjnodec; /* tesing counter for node cache adjust times */
} TCBDB;