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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_flamenco_base.h"
31 : #include "../types/fd_types.h"
32 : #include "../../ballet/wsample/fd_wsample.h"
33 :
34 217572 : #define MAX_SLOTS_CNT 432000UL
35 217572 : #define MAX_PUB_CNT 50000UL
36 :
37 : #define FD_ULONG_MAX( a, b ) (__builtin_choose_expr( __builtin_constant_p( a ) & __builtin_constant_p( b ), \
38 : ((ulong )(a))>=((ulong )(b)) ? ((ulong )(a)) : ((ulong )(b)), \
39 : fd_ulong_max( (a), (b) ) ))
40 :
41 : /* FD_EPOCH_LEADERS_{ALIGN,FOOTPRINT} are compile-time-friendly versions
42 : of the fd_epoch_leaders_{align,footprint} functions. */
43 :
44 217572 : #define FD_EPOCH_LEADERS_ALIGN (64UL)
45 : #define FD_EPOCH_LEADERS_FOOTPRINT( pub_cnt, slot_cnt ) \
46 223767 : ( FD_LAYOUT_FINI( FD_LAYOUT_APPEND( FD_LAYOUT_APPEND( \
47 223767 : FD_LAYOUT_INIT, \
48 223767 : alignof(fd_epoch_leaders_t), sizeof(fd_epoch_leaders_t) ), \
49 223767 : alignof(uint), ( \
50 223767 : (slot_cnt+FD_EPOCH_SLOTS_PER_ROTATION-1UL)/FD_EPOCH_SLOTS_PER_ROTATION*sizeof(uint) \
51 223767 : ) ), \
52 223767 : FD_EPOCH_LEADERS_ALIGN ) + \
53 223767 : FD_ULONG_ALIGN_UP( FD_ULONG_MAX( 32UL*((pub_cnt)+1UL), \
54 223767 : FD_WSAMPLE_FOOTPRINT( pub_cnt, 0 ) ), 64UL ) )
55 :
56 6705537 : #define FD_EPOCH_SLOTS_PER_ROTATION (4UL)
57 :
58 : /* fd_epoch_leaders_t contains the leader schedule of a Solana epoch. */
59 :
60 : struct fd_epoch_leaders {
61 : /* This struct contains the schedule for epoch `epoch` which spans
62 : slots [slot0, slot0+slot_cnt). */
63 : ulong epoch;
64 : ulong slot0;
65 : ulong slot_cnt;
66 :
67 : /* pub is a lookup table for node public keys with length pub_cnt */
68 : fd_pubkey_t * pub;
69 : ulong pub_cnt;
70 :
71 : /* sched contains the leader schedule in the form of indexes into
72 : the pub array. For sched_cnt, refer to below. */
73 : uint * sched;
74 : ulong sched_cnt;
75 : };
76 : typedef struct fd_epoch_leaders fd_epoch_leaders_t;
77 :
78 : FD_PROTOTYPES_BEGIN
79 :
80 : /* fd_epoch_leaders_{align,footprint} describe the required footprint
81 : and alignment of the leader schedule object. pub_cnt is the number
82 : of unique public keys. slot_cnt is the number of slots in the
83 : epoch. */
84 :
85 : FD_FN_CONST ulong
86 : fd_epoch_leaders_align( void );
87 :
88 : FD_FN_CONST ulong
89 : fd_epoch_leaders_footprint( ulong pub_cnt,
90 : ulong slot_cnt );
91 :
92 : /* fd_epoch_leaders_new formats a memory region for use as a leader
93 : schedule object. shmem points to the first byte of a memory region
94 : with matching alignment and footprint requirements. The leader
95 : schedule object will contain the leader schedule for epoch `epoch`
96 : which spans slots [slot0, slot0+slot_cnt). `slot0` must be the first
97 : slot in the epoch, but slot_cnt can be less than the length of the
98 : epoch to derive only the first portion of the leader schedule.
99 : pub_cnt is the number of unique public keys in this schedule.
100 : `stakes` points to the first entry of pub_cnt entries of stake
101 : weights sorted by tuple (stake, pubkey) in descending order.
102 :
103 : If `stakes` does not include all staked nodes, e.g. in the case of an
104 : attack that swamps the network with fake validators, `stakes` should
105 : contain the first `pub_cnt` of them in the normal sort order, and the
106 : sum of the remaining stake must be provided in excluded_stake,
107 : measured in lamports.
108 :
109 : Does NOT retain a read interest in stakes upon return.
110 : The caller is not joined to the object on return. */
111 : void *
112 : fd_epoch_leaders_new( void * shmem,
113 : ulong epoch,
114 : ulong slot0,
115 : ulong slot_cnt,
116 : ulong pub_cnt,
117 : fd_stake_weight_t const * stakes, /* indexed [0, pub_cnt) */
118 : ulong excluded_stake );
119 :
120 : /* fd_epoch_leaders_join joins the caller to the leader schedule object.
121 : fd_epoch_leaders_leave undoes an existing join. */
122 :
123 : fd_epoch_leaders_t *
124 : fd_epoch_leaders_join( void * shleaders );
125 :
126 : void *
127 : fd_epoch_leaders_leave( fd_epoch_leaders_t * leaders );
128 :
129 : /* fd_epoch_leaders_delete unformats a memory region and returns owner-
130 : ship back to the caller. */
131 :
132 : void *
133 : fd_epoch_leaders_delete( void * shleaders );
134 :
135 : /* FD_INDETERMINATE_LEADER has base58 encoding
136 : 1111111111indeterminateLeader9QSxFYNqsXA. In hex, this pubkey ends
137 : with 0x0badf00d0badf00d. */
138 6183 : #define FD_INDETERMINATE_LEADER 0x00U,0x00U,0x00U,0x00U,0x00U,0x00U,0x00U,0x00U,0x00U,0x00U,0x99U,0xf6U,0x0fU,0x96U,0x2cU,0xddU,\
139 6183 : 0x38U,0x21U,0xf3U,0x0cU,0x16U,0x1dU,0xe3U,0x0aU,0x0bU,0xadU,0xf0U,0x0dU,0x0bU,0xadU,0xf0U,0x0dU
140 :
141 : /* fd_epoch_leaders_get returns a pointer to the selected public key
142 : given a slot. Returns NULL if slot is not in [slot0, slot0+slot_cnt)
143 : given the values supplied in fd_epoch_leaders_new.
144 :
145 : If a non-zero value was provided for excluded_stake in
146 : fd_epoch_leaders_new and a validator included in the excluded_stake
147 : is the leader for the requested slot, instead of returning the
148 : correct value (which is not known), fd_epoch_leaders_get will return
149 : a pointer to a pubkey with value FD_INDETERMINATE_LEADER. */
150 :
151 : FD_FN_PURE static inline fd_pubkey_t const *
152 : fd_epoch_leaders_get( fd_epoch_leaders_t const * leaders,
153 6693489 : ulong slot ) {
154 6693489 : ulong slot_delta = slot - leaders->slot0;
155 6693489 : if( FD_UNLIKELY( slot < leaders->slot0 ) ) return NULL;
156 6693408 : if( FD_UNLIKELY( slot_delta>=leaders->slot_cnt ) ) return NULL;
157 6693177 : return (fd_pubkey_t const *)( leaders->pub + leaders->sched[ slot_delta/FD_EPOCH_SLOTS_PER_ROTATION ] );
158 6693408 : }
159 :
160 : FD_PROTOTYPES_END
161 :
162 : #endif /* HEADER_fd_src_flamenco_leaders_fd_leaders_h */
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