From 42e1ff83c02f960325869e171f7af43b4fd96107 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Tue, 9 Dec 2014 20:58:22 +0100
Subject: [PATCH] Add some utilities to be able to build books in parts, so we
 do not need as much memory.

---
 book/Makefile      |  4 ++--
 book/binloader.cpp |  7 +++++--
 book/binmerger.cpp | 51 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 4 deletions(-)
 create mode 100644 book/binmerger.cpp

diff --git a/book/Makefile b/book/Makefile
index e850241..1b20627 100644
--- a/book/Makefile
+++ b/book/Makefile
@@ -1,7 +1,7 @@
 CXXFLAGS=-std=gnu++11 -O2 -g -Wall
 LDLIBS=-lmtbl
-all: binloader binlookup
+all: binloader binlookup binmerger
 
 .PHONY: clean
 clean:
-	$(RM) binloader binlookup
+	$(RM) binloader binlookup binmerger
diff --git a/book/binloader.cpp b/book/binloader.cpp
index 88fb5ff..a561829 100644
--- a/book/binloader.cpp
+++ b/book/binloader.cpp
@@ -1,4 +1,7 @@
 //#define _GLIBCXX_PARALLEL
+
+// Usage: ./binloader IN1 IN2 IN3 ... OUT
+
 #include <stdio.h>
 #include <vector>
 #include <mtbl.h>
@@ -26,7 +29,7 @@ int main(int argc, char **argv)
 {
 	vector<Element> elems;
 
-	for (int i = 1; i < argc; ++i) {
+	for (int i = 1; i < argc - 1; ++i) {
 		FILE *fp = fopen(argv[i], "rb");
 		if (fp == NULL) {
 			perror(argv[i]);
@@ -80,7 +83,7 @@ int main(int argc, char **argv)
 	sort(elems.begin(), elems.end());
 
 	printf("Writing SSTable...\n");
-	mtbl_writer* mtbl = mtbl_writer_init("open.mtbl", NULL);
+	mtbl_writer* mtbl = mtbl_writer_init(argv[argc - 1], NULL);
 	Count c;
 	for (int i = 0; i < elems.size(); ++i) {
 		if (elems[i].result == WHITE) {
diff --git a/book/binmerger.cpp b/book/binmerger.cpp
new file mode 100644
index 0000000..480bd83
--- /dev/null
+++ b/book/binmerger.cpp
@@ -0,0 +1,51 @@
+#include <stdio.h>
+#include <mtbl.h>
+#include <memory>
+#include <string>
+#include <string.h>
+#include <assert.h>
+#include "count.h"
+
+using namespace std;
+
+
+void merge_count(void* userdata,
+                 const uint8_t *key, size_t len_key,
+		 const uint8_t *val0, size_t len_val0,
+		 const uint8_t *val1, size_t len_val1,
+		 uint8_t **merged_val, size_t *len_merged_val)
+{
+	assert(len_val0 == sizeof(Count));
+	assert(len_val1 == sizeof(Count));
+
+	const Count* c0 = reinterpret_cast<const Count*>(val0);
+	const Count* c1 = reinterpret_cast<const Count*>(val1);
+	unique_ptr<Count> c((Count *)malloc(sizeof(Count)));  // Needs to be with malloc, per merger spec.
+
+	c->white = c0->white + c1->white;
+	c->draw = c0->draw + c1->draw;
+	c->black = c0->black + c1->black;
+	c->opening_num = c0->opening_num;  // Arbitrary choice.
+	c->sum_white_elo = c0->sum_white_elo + c1->sum_white_elo;
+	c->sum_black_elo = c0->sum_black_elo + c1->sum_black_elo;
+	c->num_elo = c0->num_elo + c1->num_elo;
+
+	*merged_val = reinterpret_cast<uint8_t *>(c.release());
+	*len_merged_val = sizeof(Count);
+}
+
+int main(int argc, char **argv)
+{
+	mtbl_merger_options* mopt = mtbl_merger_options_init();
+	mtbl_merger_options_set_merge_func(mopt, merge_count, NULL);
+	mtbl_merger* merger = mtbl_merger_init(mopt);
+
+	for (int i = 1; i < argc - 1; ++i) {
+		mtbl_reader* mtbl = mtbl_reader_init(argv[i], NULL);
+		mtbl_merger_add_source(merger, mtbl_reader_source(mtbl));
+	}
+
+	mtbl_writer* writer = mtbl_writer_init(argv[argc - 1], NULL);
+	mtbl_source_write(mtbl_merger_source(merger), writer);
+	mtbl_writer_destroy(&writer);
+}
-- 
2.39.2