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1 : #ifndef HEADER_fd_src_flamenco_leaders_fd_leaders_h
2 : #define HEADER_fd_src_flamenco_leaders_fd_leaders_h
3 :
4 : /* fd_leaders provides APIs for the Solana leader schedule.
5 : Logic is compatible with Solana mainnet as of 2023-Jul.
6 :
7 : Every slot is assigned a leader (identified by a "node identity"
8 : public key). The sequence of leaders for all slots in an epoch is
9 : called the "leader schedule". The main responsibility of the leader
10 : is to produce a block for the slot.
11 :
12 : The leader schedule is divided into sched_cnt rotations. Each
13 : rotation spans one or more slots, such that
14 :
15 : slots_per_epoch = sched_cnt * slots_per_rotation
16 :
17 : The leader can only change between rotations. An example leader
18 : schedule looks as follows (where A, B, C are node identities and each
19 : column is a slot, with 4 slots per rotation)
20 :
21 : A A A A B B B B B B B B C C C C A A A A
22 : ^ ^ ^ ^ ^
23 : rotation rotation rotation rotation rotation
24 :
25 : The mainnet epoch duration is quite long (currently 432000 slots, for
26 : more information see fd_sysvar_epoch_schedule.h). To save space, we
27 : dedup pubkeys into a lookup table and only store an index for each
28 : rotation. */
29 :
30 : #include "fd_leaders_base.h"
31 : #include "../types/fd_types.h"
32 : #include "../../ballet/wsample/fd_wsample.h"
33 :
34 24 : #define FD_ULONG_MAX( a, b ) (__builtin_choose_expr( __builtin_constant_p( a ) & __builtin_constant_p( b ), \
35 24 : ((ulong )(a))>=((ulong )(b)) ? ((ulong )(a)) : ((ulong )(b)), \
36 24 : fd_ulong_max( (a), (b) ) ))
37 :
38 : /* FD_EPOCH_LEADERS_{ALIGN,FOOTPRINT} are compile-time-friendly versions
39 : of the fd_epoch_leaders_{align,footprint} functions. */
40 :
41 0 : #define FD_EPOCH_LEADERS_ALIGN (64UL)
42 : #define FD_EPOCH_LEADERS_FOOTPRINT( pub_cnt, slot_cnt ) \
43 6330 : ( FD_LAYOUT_FINI( FD_LAYOUT_APPEND( FD_LAYOUT_APPEND( \
44 6330 : FD_LAYOUT_INIT, \
45 6330 : alignof(fd_epoch_leaders_t), sizeof(fd_epoch_leaders_t) ), \
46 6330 : alignof(uint), ( \
47 6330 : (slot_cnt+FD_EPOCH_SLOTS_PER_ROTATION-1UL)/FD_EPOCH_SLOTS_PER_ROTATION*sizeof(uint) \
48 6330 : ) ), \
49 6330 : FD_EPOCH_LEADERS_ALIGN ) + \
50 6330 : FD_ULONG_ALIGN_UP( FD_ULONG_MAX( 32UL*((pub_cnt)+1UL), \
51 6330 : FD_WSAMPLE_FOOTPRINT( pub_cnt, 0 ) ), 64UL ) )
52 :
53 6795975 : #define FD_EPOCH_SLOTS_PER_ROTATION (4UL)
54 :
55 : /* fd_epoch_leaders_t contains the leader schedule of a Solana epoch. */
56 :
57 : struct fd_epoch_leaders {
58 : /* This struct contains the schedule for epoch `epoch` which spans
59 : slots [slot0, slot0+slot_cnt). */
60 : ulong epoch;
61 : ulong slot0;
62 : ulong slot_cnt;
63 :
64 : /* pub is a lookup table for node public keys with length pub_cnt */
65 : fd_pubkey_t * pub;
66 : ulong pub_cnt;
67 :
68 : /* sched contains the leader schedule in the form of indexes into
69 : the pub array. For sched_cnt, refer to below. */
70 : uint * sched;
71 : ulong sched_cnt;
72 : };
73 : typedef struct fd_epoch_leaders fd_epoch_leaders_t;
74 :
75 : FD_PROTOTYPES_BEGIN
76 :
77 : /* fd_epoch_leaders_{align,footprint} describe the required footprint
78 : and alignment of the leader schedule object. pub_cnt is the number
79 : of unique public keys. slot_cnt is the number of slots in the
80 : epoch. */
81 :
82 : FD_FN_CONST ulong
83 : fd_epoch_leaders_align( void );
84 :
85 : FD_FN_CONST ulong
86 : fd_epoch_leaders_footprint( ulong pub_cnt,
87 : ulong slot_cnt );
88 :
89 : /* fd_epoch_leaders_new formats a memory region for use as a leader
90 : schedule object. shmem points to the first byte of a memory region
91 : with matching alignment and footprint requirements. The leader
92 : schedule object will contain the leader schedule for epoch `epoch`
93 : which spans slots [slot0, slot0+slot_cnt). `slot0` must be the first
94 : slot in the epoch, but slot_cnt can be less than the length of the
95 : epoch to derive only the first portion of the leader schedule.
96 : pub_cnt is the number of unique public keys in this schedule.
97 : `stakes` points to the first entry of pub_cnt entries of stake
98 : weights sorted by tuple (stake, pubkey) in descending order.
99 :
100 : If `stakes` does not include all staked nodes, e.g. in the case of an
101 : attack that swamps the network with fake validators, `stakes` should
102 : contain the first `pub_cnt` of them in the normal sort order, and the
103 : sum of the remaining stake must be provided in excluded_stake,
104 : measured in lamports.
105 :
106 : Does NOT retain a read interest in stakes upon return.
107 : The caller is not joined to the object on return. */
108 : void *
109 : fd_epoch_leaders_new( void * shmem,
110 : ulong epoch,
111 : ulong slot0,
112 : ulong slot_cnt,
113 : ulong pub_cnt,
114 : fd_stake_weight_t const * stakes, /* indexed [0, pub_cnt) */
115 : ulong excluded_stake );
116 :
117 : /* fd_epoch_leaders_join joins the caller to the leader schedule object.
118 : fd_epoch_leaders_leave undoes an existing join. */
119 :
120 : fd_epoch_leaders_t *
121 : fd_epoch_leaders_join( void * shleaders );
122 :
123 : void *
124 : fd_epoch_leaders_leave( fd_epoch_leaders_t * leaders );
125 :
126 : /* fd_epoch_leaders_delete unformats a memory region and returns owner-
127 : ship back to the caller. */
128 :
129 : void *
130 : fd_epoch_leaders_delete( void * shleaders );
131 :
132 : /* FD_INDETERMINATE_LEADER has base58 encoding
133 : 1111111111indeterminateLeader9QSxFYNqsXA. In hex, this pubkey ends
134 : with 0x0badf00d0badf00d. */
135 6318 : #define FD_INDETERMINATE_LEADER 0x00U,0x00U,0x00U,0x00U,0x00U,0x00U,0x00U,0x00U,0x00U,0x00U,0x99U,0xf6U,0x0fU,0x96U,0x2cU,0xddU,\
136 6318 : 0x38U,0x21U,0xf3U,0x0cU,0x16U,0x1dU,0xe3U,0x0aU,0x0bU,0xadU,0xf0U,0x0dU,0x0bU,0xadU,0xf0U,0x0dU
137 :
138 : /* fd_epoch_leaders_get returns a pointer to the selected public key
139 : given a slot. Returns NULL if slot is not in [slot0, slot0+slot_cnt)
140 : given the values supplied in fd_epoch_leaders_new.
141 :
142 : If a non-zero value was provided for excluded_stake in
143 : fd_epoch_leaders_new and a validator included in the excluded_stake
144 : is the leader for the requested slot, instead of returning the
145 : correct value (which is not known), fd_epoch_leaders_get will return
146 : a pointer to a pubkey with value FD_INDETERMINATE_LEADER. */
147 :
148 : FD_FN_PURE static inline fd_pubkey_t const *
149 : fd_epoch_leaders_get( fd_epoch_leaders_t const * leaders,
150 6783819 : ulong slot ) {
151 6783819 : ulong slot_delta = slot - leaders->slot0;
152 6783819 : if( FD_UNLIKELY( slot < leaders->slot0 ) ) return NULL;
153 6783690 : if( FD_UNLIKELY( slot_delta>=leaders->slot_cnt ) ) return NULL;
154 6783345 : return (fd_pubkey_t const *)( leaders->pub + leaders->sched[ slot_delta/FD_EPOCH_SLOTS_PER_ROTATION ] );
155 6783690 : }
156 :
157 : FD_PROTOTYPES_END
158 :
159 : #endif /* HEADER_fd_src_flamenco_leaders_fd_leaders_h */
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