NOMERGE: Add bare-minimum Session API from proposal draft

mpp/shmem-def.h.in

@@ -99,6 +99,10 @@ typedef struct {
     int num_contexts;
 } shmem_team_config_t;
 
+typedef struct {
+    size_t total_ops;
+} shmem_session_config_t;
+
 #if SHMEM_HAVE_ATTRIBUTE_VISIBILITY == 1
     __attribute__((visibility("default"))) extern shmem_team_t SHMEM_TEAM_WORLD;
     __attribute__((visibility("default"))) extern shmem_team_t SHMEM_TEAM_SHARED;
@@ -116,6 +120,10 @@ typedef struct {
 #define SHMEM_SIGNAL_SET        0
 #define SHMEM_SIGNAL_ADD        1
 
+#define SHMEM_SESSION_TOTAL_OPS       (1l<<0)
+#define SHMEM_SESSION_BATCH           (1l<<0)
+#define SHMEM_SESSION_SAME_AMO        (1l<<1)
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif

mpp/shmem_c_func.h4

@@ -638,6 +638,10 @@ define(`SHMEM_C_CTX_FETCH_OR_NBI',
 `SHMEM_FUNCTION_ATTRIBUTES void SHPRE()shmem_ctx_$1_atomic_fetch_or_nbi(shmem_ctx_t ctx, $2 *fetch, $2 *target, $2 value, int pe)')dnl
 SHMEM_DECLARE_FOR_BITWISE_AMO(`SHMEM_C_CTX_FETCH_OR_NBI')
 
+/* Session Routines */
+SHMEM_FUNCTION_ATTRIBUTES void SHPRE()shmem_session_start(shmem_ctx_t ctx, long options, const shmem_session_config_t *config, long config_mask);
+SHMEM_FUNCTION_ATTRIBUTES void SHPRE()shmem_session_stop(shmem_ctx_t ctx);
+
 /* Team Management Routines */
 SHMEM_FUNCTION_ATTRIBUTES int SHPRE()shmem_team_my_pe(shmem_team_t team);
 

src/Makefile.am

@@ -62,6 +62,7 @@ libsma_la_SOURCES = \
 	shmem_env_defs.h \
 	contexts_c.c \
 	contexts.c \
+	sessions_c.c \
 	perf_counters_c.c \
 	backtrace.c \
 	shmem_team.c \

src/sessions_c.c

@@ -0,0 +1,58 @@
+/* -*- C -*-
+ *
+ * Copyright (c) 2024 Intel Corporation. All rights reserved.
+ * This software is available to you under the BSD license.
+ *
+ * This file is part of the Sandia OpenSHMEM software package. For license
+ * information, see the LICENSE file in the top level directory of the
+ * distribution.
+ *
+ */
+
+#include "config.h"
+
+#define SHMEM_INTERNAL_INCLUDE
+#include "shmem.h"
+#include "shmem_internal.h"
+#include "transport.h"
+
+#ifdef ENABLE_PROFILING
+#include "pshmem.h"
+
+#pragma weak shmem_session_start = pshmem_session_start
+#define shmem_session_start pshmem_session_start
+
+#pragma weak shmem_session_stop = pshmem_session_stop
+#define shmem_session_stop pshmem_session_stop
+
+#endif /* ENABLE_PROFILING */
+
+SHMEM_FUNCTION_ATTRIBUTES void
+shmem_session_start(shmem_ctx_t ctx, long options, const shmem_session_config_t *config, long config_mask)
+{
+    SHMEM_ERR_CHECK_INITIALIZED();
+
+    int ret = shmem_transport_session_start((shmem_transport_ctx_t *) ctx, options, config, config_mask);
+    if (0 != ret) {
+        DEBUG_MSG("Session did not start correctly (%d)\n", ret);
+    } else {
+        DEBUG_MSG("Session started correctly, but all hints are currently ignored\n");
+    }
+
+    return;
+}
+
+SHMEM_FUNCTION_ATTRIBUTES void
+shmem_session_stop(shmem_ctx_t ctx)
+{
+    SHMEM_ERR_CHECK_INITIALIZED();
+
+    int ret = shmem_transport_session_stop((shmem_transport_ctx_t *) ctx);
+    if (0 != ret) {
+        DEBUG_MSG("Session didn't stop correctly (%d)\n", ret);
+    } else {
+        DEBUG_MSG("Session stopped successfully\n");
+    }
+
+    return;
+}

src/transport_none.h

@@ -370,4 +370,18 @@ void shmem_transport_pcntr_get_all(shmem_transport_ctx_t *ctx, shmemx_pcntr_t *p
     return;
 }
 
+static inline
+int
+shmem_transport_session_start(shmem_transport_ctx_t *ctx, long options, const shmem_session_config_t *config, long config_mask)
+{
+    return 0;
+}
+
+static inline
+int
+shmem_transport_session_stop(shmem_transport_ctx_t *ctx)
+{
+    return 0;
+}
+
 #endif /* TRANSPORT_NONE_H */

src/transport_ofi.c

@@ -2123,6 +2123,16 @@ void shmem_transport_ctx_destroy(shmem_transport_ctx_t *ctx)
     }
 }
 
+int shmem_transport_session_start(shmem_transport_ctx_t *ctx, long options, const shmem_session_config_t *config, long config_mask)
+{
+    return 0;
+}
+
+int shmem_transport_session_stop(shmem_transport_ctx_t *ctx)
+{
+    return 0;
+}
+
 int shmem_transport_fini(void)
 {
     int ret;

src/transport_ofi.h

@@ -348,6 +348,9 @@ void shmem_transport_probe(void)
 int shmem_transport_ctx_create(struct shmem_internal_team_t *team, long options, shmem_transport_ctx_t **ctx);
 void shmem_transport_ctx_destroy(shmem_transport_ctx_t *ctx);
 
+int shmem_transport_session_start(shmem_transport_ctx_t *ctx, long options, const shmem_session_config_t *config, long config_mask);
+int shmem_transport_session_stop(shmem_transport_ctx_t *ctx);
+
 int shmem_transport_init(void);
 int shmem_transport_startup(void);
 int shmem_transport_fini(void);

src/transport_portals4.c

@@ -349,6 +349,18 @@ shmem_transport_ctx_destroy(shmem_transport_ctx_t *ctx)
     return;
 }
 
+int
+shmem_transport_session_start(shmem_transport_ctx_t *ctx, long options, const shmem_session_config_t *config, long config_mask)
+{
+    return 0;
+}
+
+int
+shmem_transport_session_stop(shmem_transport_ctx_t *ctx)
+{
+    return 0;
+}
+
 static
 void
 init_bounce_buffer(shmem_free_list_item_t *item)

src/transport_portals4.h

@@ -150,6 +150,9 @@ extern shmem_transport_ctx_t shmem_transport_ctx_default;
 int shmem_transport_ctx_create(struct shmem_internal_team_t *team, long options, shmem_transport_ctx_t **ctx);
 void shmem_transport_ctx_destroy(shmem_transport_ctx_t *ctx);
 
+int shmem_transport_session_start(shmem_transport_ctx_t *ctx, long options, const shmem_session_config_t *config, long config_mask);
+int shmem_transport_session_stop(shmem_transport_ctx_t *ctx);
+
 /*
  * PORTALS4_GET_REMOTE_ACCESS is used to get the correct PT and offset
  * from the base of the list entry on that PT for a given target

src/transport_ucx.h

@@ -198,6 +198,20 @@ shmem_transport_ctx_destroy(shmem_transport_ctx_t *ctx)
     return;
 }
 
+static inline
+int
+shmem_transport_session_start(shmem_transport_ctx_t *ctx, long options, const shmem_session_config_t *config, long config_mask)
+{
+    return 0;
+}
+
+static inline
+int
+shmem_transport_session_stop(shmem_transport_ctx_t *ctx)
+{
+      return 0;
+}
+
 static inline
 int
 shmem_transport_quiet(shmem_transport_ctx_t* ctx)

test/spec-example/shmem_session_example.c

@@ -0,0 +1,54 @@
+/*                                                                                                                                                                                                                                           *  This test program is derived from an example program in the
+ *  OpenSHMEM specification.
+ */
+
+#include <shmem.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#define N_UPDATES (1lu << 18)
+#define N_INDICES (1lu << 10)
+#define N_VALUES  (1lu << 31)
+
+int main(void) {
+
+  shmem_init();
+
+  uint64_t *table = shmem_calloc(N_INDICES, sizeof(uint64_t));
+
+  int mype = shmem_my_pe();
+  int npes = shmem_n_pes();
+  srand(mype);
+
+  shmem_ctx_t ctx;
+  int ret = shmem_ctx_create(0, &ctx);
+  if (ret != 0) {
+      printf("%d: Error creating context (%d)\n", mype, ret);
+      shmem_global_exit(1);
+  }
+
+  shmem_session_config_t config;
+  long config_mask;
+  config.total_ops = N_UPDATES;
+  config_mask = SHMEM_SESSION_TOTAL_OPS;
+
+  shmem_session_start(ctx, SHMEM_SESSION_SAME_AMO, &config, config_mask);
+
+  for (size_t i = 0; i < N_UPDATES; i++) {
+      int random_pe = rand() % npes;
+      size_t random_idx = rand() % N_INDICES;
+      uint64_t random_val = rand() % N_VALUES;
+      shmem_ctx_uint64_atomic_xor(ctx, &table[random_idx], random_val, random_pe);
+  }
+
+  shmem_session_stop(ctx);
+  shmem_ctx_quiet(ctx);    /* shmem_session_stop() does not quiet the context. */
+  shmem_sync_all();        /* shmem_session_stop() does not synchronize.       */
+
+  /* At this point, it is safe to check and/or validate the table result... */
+
+  shmem_ctx_destroy(ctx);
+  shmem_free(table);
+  shmem_finalize();
+  return 0;
+}