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89 lines
3 KiB
C
89 lines
3 KiB
C
#include "cachetable.h"
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#include "hashtable.h"
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#include "pma.h"
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#include "brt.h"
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//#include "pma.h"
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typedef long long diskoff; /* Offset in a disk. -1 is the NULL pointer. */
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enum { TREE_FANOUT = 16 }; //, NODESIZE=1<<20 };
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enum { KEY_VALUE_OVERHEAD = 8 }; /* Must store the two lengths. */
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struct nodeheader_in_file {
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int n_in_buffer;
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};
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enum { BUFFER_HEADER_SIZE = (4 // height//
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+ 4 // n_children
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+ TREE_FANOUT * 8 // children
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) };
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typedef struct brtnode *BRTNODE;
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/* Internal nodes. */
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struct brtnode {
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enum typ_tag tag;
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unsigned int nodesize;
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diskoff thisnodename;
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int height; /* height is always >= 0. 0 for leaf, >0 for nonleaf. */
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union node {
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struct nonleaf {
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int n_children; /* if n_children==TREE_FANOUT+1 then the tree needs to be rebalanced. */
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bytevec childkeys[TREE_FANOUT]; /* Pivot keys. Child 0's keys are <= childkeys[0]. Child 1's keys are <= childkeys[1].
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Note: It is possible that Child 1's keys are == to child 0's key's, so it is
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not necessarily true that child 1's keys are > childkeys[0].
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However, in the absense of duplicate keys, child 1's keys *are* > childkeys[0]. */
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unsigned int childkeylens[TREE_FANOUT];
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unsigned int totalchildkeylens;
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diskoff children[TREE_FANOUT+1]; /* unused if height==0 */ /* Note: The last element of these arrays is used only temporarily while splitting a node. */
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HASHTABLE htables[TREE_FANOUT+1];
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unsigned int n_bytes_in_hashtable[TREE_FANOUT+1]; /* how many bytes are in each hashtable (including overheads) */
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unsigned int n_bytes_in_hashtables;
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} n;
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struct leaf {
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PMA buffer;
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unsigned int n_bytes_in_buffer;
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} l;
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} u;
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};
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struct brt_header {
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int dirty;
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unsigned int nodesize;
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diskoff freelist;
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diskoff unused_memory;
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diskoff unnamed_root;
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int n_named_roots; /* -1 if the only one is unnamed */
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char **names;
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diskoff *roots;
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};
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struct brt {
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CACHEFILE cf;
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char *database_name;
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// The header is shared. It is also ephemeral.
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struct brt_header *h;
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BRT_CURSOR cursors_head, cursors_tail;
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};
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/* serialization code */
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void serialize_brtnode_to(int fd, diskoff off, diskoff size, BRTNODE node);
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int deserialize_brtnode_from (int fd, diskoff off, BRTNODE *brtnode, int nodesize);
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unsigned int serialize_brtnode_size(BRTNODE node); /* How much space will it take? */
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unsigned int brtnode_which_child (BRTNODE node, bytevec key, ITEMLEN keylen);
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int keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2len);
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void verify_counts(BRTNODE);
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int serialize_brt_header_to (int fd, struct brt_header *h);
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int deserialize_brtheader_from (int fd, diskoff off, struct brt_header **brth);
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static inline int brtnode_n_hashtables(BRTNODE node) { if (node->height==0) return 1; else return node->u.n.n_children; }
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//int write_brt_header (int fd, struct brt_header *header);
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#if 1
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#define DEADBEEF ((void*)0xDEADBEEF)
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#else
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#define DEADBEEF ((void*)0xDEADBEEFDEADBEEF)
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#endif
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