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https://github.com/XTXMarkets/ternfs.git
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110705db8d
Things not done because probably disruptive: * kmod filesystem string * sysctl/debugfs/trace * metrics names * xmon instance names Some of these might be renamed too, but starting with a relatively safe set.
99 lines
2.5 KiB
C++
99 lines
2.5 KiB
C++
// wyhash is chosen because it has 64-bit state (easy to bind to go),
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// and it only has one addition in the dependency chain.
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//
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// Actual code from <https://github.com/lemire/testingRNG/blob/450eea89646c056415686e3b8b58c662a3cdc2d2/source/wyhash.h>.
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#ifndef TERN_WYHASH
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#define TERN_WYHASH
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#include <stdint.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <unistd.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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__attribute__((unused))
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#ifdef __clang__
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__attribute__((no_sanitize("integer")))
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#endif
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inline uint64_t wyhash64(uint64_t* state) {
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*state += UINT64_C(0x60bee2bee120fc15);
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__uint128_t tmp;
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tmp = (__uint128_t)*state * UINT64_C(0xa3b195354a39b70d);
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uint64_t m1 = (tmp >> 64) ^ tmp;
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tmp = (__uint128_t)m1 * UINT64_C(0x1b03738712fad5c9);
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uint64_t m2 = (tmp >> 64) ^ tmp;
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return m2;
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}
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__attribute__((unused))
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inline double wyhash64_double(uint64_t* state) {
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return ((double)(wyhash64(state) >> 11) * 0x1.0p-53);
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}
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__attribute__((unused))
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static void wyhash64_bytes(uint64_t* state, uint8_t* bytes, size_t len) {
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uint8_t* end = bytes+len;
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uint8_t* unaligned_end = (uint8_t*)(((uintptr_t)bytes - 1 + 8) & ~7u);
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for (; bytes < unaligned_end; bytes++) {
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*bytes = wyhash64(state) & 0xFF;
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}
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uint64_t* words = (uint64_t*)bytes;
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for (; (uint8_t*)(words + 1) <= end; words++) {
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*words = wyhash64(state);
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}
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for (bytes = (uint8_t*)words; bytes < end; bytes++) {
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*bytes = wyhash64(state) & 0xFF;
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}
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}
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// Not specific to wyhash, just handy
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__attribute__((unused))
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static uint64_t wyhash64_rand() {
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int fd = open("/dev/urandom", O_RDONLY);
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if (fd < 0) {
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fprintf(stderr, "could not open /dev/urandom: %d", errno);
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exit(1);
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}
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uint64_t x;
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ssize_t r = read(fd, &x, sizeof(x));
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if (r < 0) {
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fprintf(stderr, "could read /dev/urandom: %d", errno);
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exit(1);
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}
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if (r != sizeof(x)) {
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fprintf(stderr, "expected %ld bytes from /dev/urandom, got %ld", sizeof(x), r);
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exit(1);
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}
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if (close(fd) < 0) {
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fprintf(stderr, "could not close /dev/urandom: %d", errno);
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exit(1);
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}
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return x;
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}
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#ifdef __cplusplus
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}
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#endif
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#ifdef __cplusplus
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struct wyhash64_gen {
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private:
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uint64_t _s;
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public:
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wyhash64_gen(uint64_t s): _s(s) {}
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using result_type = uint64_t;
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static constexpr uint64_t min() { return 0; }
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static constexpr uint64_t max() { return ~(uint64_t)0; }
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uint64_t operator()() { return wyhash64(&_s); }
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};
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#endif
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#endif |