* pgpool: a language independent connection pool server for PostgreSQL
* written by Tatsuo Ishii
*
- * Copyright (c) 2003-2024 PgPool Global Development Group
+ * Copyright (c) 2003-2025 PgPool Global Development Group
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose and without fee is hereby
#include "pool_config_variables.h"
#include "utils/palloc.h"
#include "utils/memutils.h"
+#include "utils/pg_prng.h"
#include "utils/pool_ssl.h"
#include "utils/pool_ipc.h"
#include "utils/pool_relcache.h"
static bool unix_fds_not_isset(int* fds, int num_unix_fds, fd_set* opt);
+static void initialize_prng(void);
+static TimestampTz GetCurrentTimestamp(void);
+
/*
* Non 0 means SIGTERM (smart shutdown) or SIGINT (fast shutdown) has arrived
*/
*/
static bool connection_pool_initialized = false;
+/*
+ * prng state
+ */
+pg_prng_state prng_state_d;
+pg_prng_state *prng_state;
+
/*
* child main loop
*/
{
sigjmp_buf local_sigjmp_buf;
POOL_CONNECTION_POOL *volatile backend = NULL;
- struct timeval now;
- struct timezone tz;
/* counter for child_max_connections. "volatile" declaration is necessary
* so that this is counted up even if long jump is issued due to
pool_init_process_context();
/* initialize random seed */
- gettimeofday(&now, &tz);
-
-#if defined(sun) || defined(__sun)
- srand((unsigned int) now.tv_usec);
-#else
- srandom((unsigned int) now.tv_usec);
-#endif
+ prng_state = &prng_state_d;
+ initialize_prng();
/* initialize connection pool */
if (pool_init_cp())
{
pool_get_my_process_info()->status = status;
}
+
+/*
+ * imported from backend/utils/adt/timestamp.c
+ */
+/*
+ * GetCurrentTimestamp -- get the current operating system time
+ *
+ * Result is in the form of a TimestampTz value, and is expressed to the
+ * full precision of the gettimeofday() syscall
+ */
+static TimestampTz
+GetCurrentTimestamp(void)
+{
+ TimestampTz result;
+ struct timeval tp;
+
+ gettimeofday(&tp, NULL);
+
+ result = (TimestampTz) tp.tv_sec -
+ ((POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY);
+ result = (result * USECS_PER_SEC) + tp.tv_usec;
+
+ return result;
+}
+
+/*
+ * imported from backend/utils/adt/pseudorandomfuncs.c
+ * and modified.
+ */
+/*
+ * initialize_prng() -
+ *
+ * Initialize (seed) the PRNG, if not done yet in this process.
+ */
+static void
+initialize_prng(void)
+{
+ /*
+ * If possible, seed the PRNG using high-quality random bits. Should
+ * that fail for some reason, we fall back on a lower-quality seed
+ * based on current time and PID.
+ */
+ if (!pg_prng_strong_seed(prng_state))
+ {
+ TimestampTz now = GetCurrentTimestamp();
+ uint64 iseed;
+
+ /* Mix the PID with the most predictable bits of the timestamp */
+ iseed = (uint64) now ^ ((uint64) getpid() << 32);
+ pg_prng_seed(prng_state, iseed);
+ }
+}
* pgpool: a language independent connection pool server for PostgreSQL
* written by Tatsuo Ishii
*
- * Copyright (c) 2003-2020 PgPool Global Development Group
+ * Copyright (c) 2003-2025 PgPool Global Development Group
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose and without fee is hereby
#include "protocol/pool_connection_pool.h"
#include "utils/palloc.h"
#include "utils/memutils.h"
+#include "utils/pg_prng.h"
#include "utils/pool_ipc.h"
#include "utils/pool_stream.h"
#include "utils/pool_ssl.h"
static void si_enter_critical_region(void);
static void si_leave_critical_region(void);
+extern pg_prng_state *prng_state;
+
/*
* create a persistent connection
*/
*/
int suggested_node_id = -2;
-#if defined(sun) || defined(__sun)
- r = (((double) rand()) / RAND_MAX);
-#else
- r = (((double) random()) / RAND_MAX);
-#endif
+ r = pg_prng_double(prng_state);
+// elog(LOG, "pg_prng_double: %f", r);
/*
* Check user_redirect_preference_list
}
}
-#if defined(sun) || defined(__sun)
- r = (((double) rand()) / RAND_MAX) * total_weight;
-#else
- r = (((double) random()) / RAND_MAX) * total_weight;
-#endif
+ r = pg_prng_double(prng_state) * total_weight;
selected_slot = PRIMARY_NODE_ID;
total_weight = 0.0;
}
}
-#if defined(sun) || defined(__sun)
- r = (((double) rand()) / RAND_MAX) * total_weight;
-#else
- r = (((double) random()) / RAND_MAX) * total_weight;
-#endif
+ r = pg_prng_double(prng_state) * total_weight;
total_weight = 0.0;
for (i = 0; i < NUM_BACKENDS; i++)
}
}
-#if defined(sun) || defined(__sun)
- r = (((double) rand()) / RAND_MAX) * total_weight;
-#else
- r = (((double) random()) / RAND_MAX) * total_weight;
-#endif
+ r = pg_prng_double(prng_state) * total_weight;
selected_slot = PRIMARY_NODE_ID;
--- /dev/null
+/*
+ * This file was imported from PostgreSQL source code
+ * (src/common/pg_prng.c).
+ */
+
+/*-------------------------------------------------------------------------
+ *
+ * Pseudo-Random Number Generator
+ *
+ * We use Blackman and Vigna's xoroshiro128** 1.0 algorithm
+ * to have a small, fast PRNG suitable for generating reasonably
+ * good-quality 64-bit data. This should not be considered
+ * cryptographically strong, however.
+ *
+ * About these generators: https://prng.di.unimi.it/
+ * See also https://en.wikipedia.org/wiki/List_of_random_number_generators
+ *
+ * Portions Copyright (c) 2025, PgPool Global Development Group
+ * Portions Copyright (c) 2021-2025, PostgreSQL Global Development Group
+ *
+ * src/common/pg_prng.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "pool.h"
+
+#include <math.h>
+
+#include "utils/pg_prng.h"
+
+/* X/Open (XSI) requires <math.h> to provide M_PI, but core POSIX does not */
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
+
+
+/* process-wide state vector */
+pg_prng_state pg_global_prng_state;
+
+/* ignore likely/unlikely */
+#define likely
+#define unlikely
+
+/*
+ * 64-bit rotate left
+ */
+static inline uint64
+rotl(uint64 x, int bits)
+{
+ return (x << bits) | (x >> (64 - bits));
+}
+
+/*
+ * The basic xoroshiro128** algorithm.
+ * Generates and returns a 64-bit uniformly distributed number,
+ * updating the state vector for next time.
+ *
+ * Note: the state vector must not be all-zeroes, as that is a fixed point.
+ */
+static uint64
+xoroshiro128ss(pg_prng_state *state)
+{
+ uint64 s0 = state->s0,
+ sx = state->s1 ^ s0,
+ val = rotl(s0 * 5, 7) * 9;
+
+ /* update state */
+ state->s0 = rotl(s0, 24) ^ sx ^ (sx << 16);
+ state->s1 = rotl(sx, 37);
+
+ return val;
+}
+
+/*
+ * We use this generator just to fill the xoroshiro128** state vector
+ * from a 64-bit seed.
+ */
+static uint64
+splitmix64(uint64 *state)
+{
+ /* state update */
+ uint64 val = (*state += UINT64CONST(0x9E3779B97f4A7C15));
+
+ /* value extraction */
+ val = (val ^ (val >> 30)) * UINT64CONST(0xBF58476D1CE4E5B9);
+ val = (val ^ (val >> 27)) * UINT64CONST(0x94D049BB133111EB);
+
+ return val ^ (val >> 31);
+}
+
+/*
+ * Initialize the PRNG state from a 64-bit integer,
+ * taking care that we don't produce all-zeroes.
+ */
+void
+pg_prng_seed(pg_prng_state *state, uint64 seed)
+{
+ state->s0 = splitmix64(&seed);
+ state->s1 = splitmix64(&seed);
+ /* Let's just make sure we didn't get all-zeroes */
+ (void) pg_prng_seed_check(state);
+}
+
+/*
+ * Initialize the PRNG state from a double in the range [-1.0, 1.0],
+ * taking care that we don't produce all-zeroes.
+ */
+void
+pg_prng_fseed(pg_prng_state *state, double fseed)
+{
+ /* Assume there's about 52 mantissa bits; the sign contributes too. */
+ int64 seed = ((double) ((UINT64CONST(1) << 52) - 1)) * fseed;
+
+ pg_prng_seed(state, (uint64) seed);
+}
+
+/*
+ * Validate a PRNG seed value.
+ */
+bool
+pg_prng_seed_check(pg_prng_state *state)
+{
+ /*
+ * If the seeding mechanism chanced to produce all-zeroes, insert
+ * something nonzero. Anything would do; use Knuth's LCG parameters.
+ */
+ if (unlikely(state->s0 == 0 && state->s1 == 0))
+ {
+ state->s0 = UINT64CONST(0x5851F42D4C957F2D);
+ state->s1 = UINT64CONST(0x14057B7EF767814F);
+ }
+
+ /* As a convenience for the pg_prng_strong_seed macro, return true */
+ return true;
+}
+
+/*
+ * Select a random uint64 uniformly from the range [0, PG_UINT64_MAX].
+ */
+uint64
+pg_prng_uint64(pg_prng_state *state)
+{
+ return xoroshiro128ss(state);
+}
+
+/*
+ * We ignore some functions because we do not port pg_bitutils.c (yet).
+ */
+#ifdef NOT_USED
+/*
+ * Select a random uint64 uniformly from the range [rmin, rmax].
+ * If the range is empty, rmin is always produced.
+ */
+uint64
+pg_prng_uint64_range(pg_prng_state *state, uint64 rmin, uint64 rmax)
+{
+ uint64 val;
+
+ if (likely(rmax > rmin))
+ {
+ /*
+ * Use bitmask rejection method to generate an offset in 0..range.
+ * Each generated val is less than twice "range", so on average we
+ * should not have to iterate more than twice.
+ */
+ uint64 range = rmax - rmin;
+ uint32 rshift = 63 - pg_leftmost_one_pos64(range);
+
+ do
+ {
+ val = xoroshiro128ss(state) >> rshift;
+ } while (val > range);
+ }
+ else
+ val = 0;
+
+ return rmin + val;
+}
+
+/*
+ * Select a random int64 uniformly from the range [PG_INT64_MIN, PG_INT64_MAX].
+ */
+int64
+pg_prng_int64(pg_prng_state *state)
+{
+ return (int64) xoroshiro128ss(state);
+}
+#endif
+
+/*
+ * Select a random int64 uniformly from the range [0, PG_INT64_MAX].
+ */
+int64
+pg_prng_int64p(pg_prng_state *state)
+{
+ return (int64) (xoroshiro128ss(state) & UINT64CONST(0x7FFFFFFFFFFFFFFF));
+}
+
+#ifdef NOT_USED
+/*
+ * Select a random int64 uniformly from the range [rmin, rmax].
+ * If the range is empty, rmin is always produced.
+ */
+int64
+pg_prng_int64_range(pg_prng_state *state, int64 rmin, int64 rmax)
+{
+ int64 val;
+
+ if (likely(rmax > rmin))
+ {
+ uint64 uval;
+
+ /*
+ * Use pg_prng_uint64_range(). Can't simply pass it rmin and rmax,
+ * since (uint64) rmin will be larger than (uint64) rmax if rmin < 0.
+ */
+ uval = (uint64) rmin +
+ pg_prng_uint64_range(state, 0, (uint64) rmax - (uint64) rmin);
+
+ /*
+ * Safely convert back to int64, avoiding implementation-defined
+ * behavior for values larger than PG_INT64_MAX. Modern compilers
+ * will reduce this to a simple assignment.
+ */
+ if (uval > PG_INT64_MAX)
+ val = (int64) (uval - PG_INT64_MIN) + PG_INT64_MIN;
+ else
+ val = (int64) uval;
+ }
+ else
+ val = rmin;
+
+ return val;
+}
+#endif
+
+/*
+ * Select a random uint32 uniformly from the range [0, PG_UINT32_MAX].
+ */
+uint32
+pg_prng_uint32(pg_prng_state *state)
+{
+ /*
+ * Although xoroshiro128** is not known to have any weaknesses in
+ * randomness of low-order bits, we prefer to use the upper bits of its
+ * result here and below.
+ */
+ uint64 v = xoroshiro128ss(state);
+
+ return (uint32) (v >> 32);
+}
+
+/*
+ * Select a random int32 uniformly from the range [PG_INT32_MIN, PG_INT32_MAX].
+ */
+int32
+pg_prng_int32(pg_prng_state *state)
+{
+ uint64 v = xoroshiro128ss(state);
+
+ return (int32) (v >> 32);
+}
+
+/*
+ * Select a random int32 uniformly from the range [0, PG_INT32_MAX].
+ */
+int32
+pg_prng_int32p(pg_prng_state *state)
+{
+ uint64 v = xoroshiro128ss(state);
+
+ return (int32) (v >> 33);
+}
+
+/*
+ * Select a random double uniformly from the range [0.0, 1.0).
+ *
+ * Note: if you want a result in the range (0.0, 1.0], the standard way
+ * to get that is "1.0 - pg_prng_double(state)".
+ */
+double
+pg_prng_double(pg_prng_state *state)
+{
+ uint64 v = xoroshiro128ss(state);
+
+ /*
+ * As above, assume there's 52 mantissa bits in a double. This result
+ * could round to 1.0 if double's precision is less than that; but we
+ * assume IEEE float arithmetic elsewhere in Postgres, so this seems OK.
+ */
+ return ldexp((double) (v >> (64 - 52)), -52);
+}
+
+/*
+ * Select a random double from the normal distribution with
+ * mean = 0.0 and stddev = 1.0.
+ *
+ * To get a result from a different normal distribution use
+ * STDDEV * pg_prng_double_normal() + MEAN
+ *
+ * Uses https://en.wikipedia.org/wiki/Box%E2%80%93Muller_transform
+ */
+double
+pg_prng_double_normal(pg_prng_state *state)
+{
+ double u1,
+ u2,
+ z0;
+
+ /*
+ * pg_prng_double generates [0, 1), but for the basic version of the
+ * Box-Muller transform the two uniformly distributed random numbers are
+ * expected to be in (0, 1]; in particular we'd better not compute log(0).
+ */
+ u1 = 1.0 - pg_prng_double(state);
+ u2 = 1.0 - pg_prng_double(state);
+
+ /* Apply Box-Muller transform to get one normal-valued output */
+ z0 = sqrt(-2.0 * log(u1)) * sin(2.0 * M_PI * u2);
+ return z0;
+}
+
+/*
+ * Select a random boolean value.
+ */
+bool
+pg_prng_bool(pg_prng_state *state)
+{
+ uint64 v = xoroshiro128ss(state);
+
+ return (bool) (v >> 63);
+}
projects / pgpool2.git / commitdiff