Add comments, fix formatting, and add allocator stats emitter.

Author: tonyastolfi

.clang-format

@@ -1,5 +1,5 @@
 ---
-Language:        Cpp
+Language:        C
 # BasedOnStyle:  LLVM
 AccessModifierOffset: -3
 AlignAfterOpenBracket: Align

include/splinterdb/splinterdb.h

@@ -418,6 +418,17 @@ splinterdb_stats_print_insertion(const splinterdb *kvs);
 void
 splinterdb_stats_print_lookup(const splinterdb *kvs);
 
+void
+splinterdb_stats_reset(splinterdb *kvs);
+
+/*
+ * Statistics Emitters
+ *
+ * Reports insertion or lookup statistics by calling the passed
+ * function with the passed void* data pointer.  For programmatic
+ * access to stats without having to parse the output
+ * of splinterdb_stats_print_{insertion|lookup}
+ */
 void
 splinterdb_stats_emit_insertion(const splinterdb *kvs,
                                 void             *user_data,
@@ -428,7 +439,4 @@ splinterdb_stats_emit_lookup(const splinterdb *kvs,
                              void             *user_data,
                              emit_stat_fn      user_fn);
 
-void
-splinterdb_stats_reset(splinterdb *kvs);
-
 #endif // _SPLINTERDB_H_

src/allocator.h

@@ -1,6 +1,8 @@
 // Copyright 2018-2021 VMware, Inc.
 // SPDX-License-Identifier: Apache-2.0
 
+// clang-format off
+
 /*
  * allocator.h --
  *
@@ -139,6 +141,7 @@ typedef uint64 (*base_addr_fn)(const allocator *al, uint64 addr);
 
 typedef void (*print_fn)(allocator *al);
 typedef void (*assert_fn)(allocator *al);
+typedef void (*emit_fn)(allocator* al, void* user_data, emit_stat_fn user_fn);
 
 /*
  * Define an abstract allocator interface, holding different allocation-related
@@ -165,6 +168,7 @@ typedef struct allocator_ops {
 
    print_fn print_stats;
    print_fn print_allocated;
+   emit_fn emit_stats;
 } allocator_ops;
 
 // To sub-class cache, make a cache your first field;
@@ -294,3 +298,10 @@ allocator_page_valid(allocator *al, uint64 addr)
       return FALSE;
    }
 }
+
+// clang-format on
+
+static inline void allocator_emit_stats(allocator* al, void* user_data, emit_stat_fn user_fn)
+{
+    return al->ops->emit_stats(al, user_data, user_fn);
+}

src/clockcache.c

@@ -2541,17 +2541,21 @@ clockcache_io_stats(clockcache *cc, uint64 *read_bytes, uint64 *write_bytes)
    *read_bytes  = read_pages * 4 * KiB;
 }
 
+// State struct for collecting cache statistics; captures common data
+// between print and emit stats functions.
+//
 typedef struct cache_stats_collection {
-    cache_stats global_stats;
-    uint64 page_writes;
-    fraction miss_time[NUM_PAGE_TYPES];
-    fraction avg_prefetch_pages[NUM_PAGE_TYPES];
-    fraction avg_write_pages;
-    
+
+   cache_stats global_stats;
+   uint64      page_writes;
+   fraction    miss_time[NUM_PAGE_TYPES];
+   fraction    avg_prefetch_pages[NUM_PAGE_TYPES];
+   fraction    avg_write_pages;
+
 } cache_stats_collection;
 
 int
-cache_stats_collection_create(clockcache *cc, cache_stats_collection* out)
+cache_stats_collection_create(clockcache *cc, cache_stats_collection *out)
 {
    if (!cc->cfg->use_stats) {
       return -1;
@@ -2562,7 +2566,8 @@ cache_stats_collection_create(clockcache *cc, cache_stats_collection* out)
    for (uint64_t i = 0; i < MAX_THREADS; i++) {
       for (page_type type = 0; type < NUM_PAGE_TYPES; type++) {
          out->global_stats.cache_hits[type] += cc->stats[i].cache_hits[type];
-         out->global_stats.cache_misses[type] += cc->stats[i].cache_misses[type];
+         out->global_stats.cache_misses[type] +=
+            cc->stats[i].cache_misses[type];
          out->global_stats.cache_miss_time_ns[type] +=
             cc->stats[i].cache_miss_time_ns[type];
          out->global_stats.page_writes[type] += cc->stats[i].page_writes[type];
@@ -2577,14 +2582,16 @@ cache_stats_collection_create(clockcache *cc, cache_stats_collection* out)
 
 
    for (page_type type = 0; type < NUM_PAGE_TYPES; type++) {
-      out->miss_time[type] =
-         init_fraction(out->global_stats.cache_miss_time_ns[type], SEC_TO_NSEC(1));
-      out->avg_prefetch_pages[type] = init_fraction(
-         out->global_stats.page_reads[type] - out->global_stats.cache_misses[type],
-         out->global_stats.prefetches_issued[type]);
+      out->miss_time[type] = init_fraction(
+         out->global_stats.cache_miss_time_ns[type], SEC_TO_NSEC(1));
+      out->avg_prefetch_pages[type] =
+         init_fraction(out->global_stats.page_reads[type]
+                          - out->global_stats.cache_misses[type],
+                       out->global_stats.prefetches_issued[type]);
    }
-   out->avg_write_pages = init_fraction(out->page_writes - out->global_stats.syncs_issued,
-                                        out->global_stats.writes_issued);   
+   out->avg_write_pages =
+      init_fraction(out->page_writes - out->global_stats.syncs_issued,
+                    out->global_stats.writes_issued);
 
    return 0;
 }
@@ -2594,9 +2601,9 @@ clockcache_print_stats(platform_log_handle *log_handle, clockcache *cc)
 {
    cache_stats_collection col;
    if (cache_stats_collection_create(cc, &col) != 0) {
-     return;
+      return;
    }
-    
+
    // clang-format off
    platform_log(log_handle, "Cache Statistics\n");
    platform_log(log_handle, "-----------------------------------------------------------------------------------------------\n");
@@ -2658,55 +2665,56 @@ clockcache_print_stats(platform_log_handle *log_handle, clockcache *cc)
    allocator_print_stats(cc->al);
 }
 
+
 void
-clockcache_emit_page_type_stats(void* user_data, emit_stat_fn user_fn,
-                                const cache_stats_collection* col,
-                                page_type type, const char* name)
+clockcache_emit_stats(void *user_data, emit_stat_fn user_fn, clockcache *cc)
 {
-    char name_buf[256];
+   cache_stats_collection col;
+   if (cache_stats_collection_create(cc, &col) != 0) {
+      return;
+   }
 
-    snprintf(name_buf, sizeof(name_buf), "splinterdb.cache.%s.hits", name);
-    user_fn(user_data, name_buf, col->global_stats.cache_hits[type]);
-    
-    snprintf(name_buf, sizeof(name_buf), "splinterdb.cache.%s.misses", name);
-    user_fn(user_data, name_buf, col->global_stats.cache_misses[type]);
-    
-    snprintf(name_buf, sizeof(name_buf), "splinterdb.cache.%s.miss_time.num", name);
-    user_fn(user_data, name_buf, col->miss_time[type].numerator);
+   user_fn(user_data, "splinterdb.cache.page_writes", col.page_writes);
 
-    snprintf(name_buf, sizeof(name_buf), "splinterdb.cache.%s.miss_time.div", name);
-    user_fn(user_data, name_buf, col->miss_time[type].denominator);
+   char name_buf[256];
 
-    snprintf(name_buf, sizeof(name_buf), "splinterdb.cache.%s.writes", name);
-    user_fn(user_data, name_buf, col->global_stats.page_writes[type]);
+   for (page_type type = PAGE_TYPE_FIRST; type < NUM_PAGE_TYPES; type++) {
+      const char *name = page_type_str[type];
 
-    snprintf(name_buf, sizeof(name_buf), "splinterdb.cache.%s.reads", name);
-    user_fn(user_data, name_buf, col->global_stats.page_reads[type]);
+      snprintf(name_buf, sizeof(name_buf), "splinterdb.cache.%s.hits", name);
+      user_fn(user_data, name_buf, col.global_stats.cache_hits[type]);
 
-    snprintf(name_buf, sizeof(name_buf), "splinterdb.cache.%s.avg_prefetch.num", name);
-    user_fn(user_data, name_buf, col->avg_prefetch_pages[type].numerator);
-    
-    snprintf(name_buf, sizeof(name_buf), "splinterdb.cache.%s.avg_prefetch.div", name);
-    user_fn(user_data, name_buf, col->avg_prefetch_pages[type].denominator);
-}
+      snprintf(name_buf, sizeof(name_buf), "splinterdb.cache.%s.misses", name);
+      user_fn(user_data, name_buf, col.global_stats.cache_misses[type]);
 
-void
-clockcache_emit_stats(void* user_data, emit_stat_fn user_fn, clockcache *cc)
-{
-   cache_stats_collection col;
-   if (cache_stats_collection_create(cc, &col) != 0) {
-     return;
-   }
+      snprintf(
+         name_buf, sizeof(name_buf), "splinterdb.cache.%s.miss_time.num", name);
+      user_fn(user_data, name_buf, col.miss_time[type].numerator);
 
-   user_fn(user_data, "splinterdb.cache.page_writes", col.page_writes);
+      snprintf(
+         name_buf, sizeof(name_buf), "splinterdb.cache.%s.miss_time.div", name);
+      user_fn(user_data, name_buf, col.miss_time[type].denominator);
+
+      snprintf(name_buf, sizeof(name_buf), "splinterdb.cache.%s.writes", name);
+      user_fn(user_data, name_buf, col.global_stats.page_writes[type]);
+
+      snprintf(name_buf, sizeof(name_buf), "splinterdb.cache.%s.reads", name);
+      user_fn(user_data, name_buf, col.global_stats.page_reads[type]);
 
-   clockcache_emit_page_type_stats(user_data, user_fn, &col, PAGE_TYPE_TRUNK, "trunk");
-   clockcache_emit_page_type_stats(user_data, user_fn, &col, PAGE_TYPE_BRANCH, "branch");
-   clockcache_emit_page_type_stats(user_data, user_fn, &col, PAGE_TYPE_MEMTABLE, "memtable");
-   clockcache_emit_page_type_stats(user_data, user_fn, &col, PAGE_TYPE_FILTER, "filter");
-   clockcache_emit_page_type_stats(user_data, user_fn, &col, PAGE_TYPE_LOG, "log");
-   clockcache_emit_page_type_stats(user_data, user_fn, &col, PAGE_TYPE_SUPERBLOCK, "superblock");
+      snprintf(name_buf,
+               sizeof(name_buf),
+               "splinterdb.cache.%s.avg_prefetch.num",
+               name);
+      user_fn(user_data, name_buf, col.avg_prefetch_pages[type].numerator);
+
+      snprintf(name_buf,
+               sizeof(name_buf),
+               "splinterdb.cache.%s.avg_prefetch.div",
+               name);
+      user_fn(user_data, name_buf, col.avg_prefetch_pages[type].denominator);
+   }
 
+   allocator_emit_stats(cc->al, user_data, user_fn);
 }
 
 void