Use ptr from mmap for GHistIndexMatrix and ColumnMatrix. (#9315)

* Use ptr from mmap for `GHistIndexMatrix` and `ColumnMatrix`.

- Define a resource for holding various types of memory pointers.
- Define ref vector for holding resources.
- Swap the underlying resources for GHist and ColumnM.
- Add documentation for current status.
- s390x support is removed. It should work if you can compile XGBoost, all the old workaround code does is to get GCC to compile.

tests/cpp/common/test_io.cc

@@ -3,11 +3,12 @@
  */
 #include <gtest/gtest.h>
 
-#include <fstream>
+#include <cstddef>  // for size_t
+#include <fstream>  // for ofstream
 
 #include "../../../src/common/io.h"
-#include "../helpers.h"
 #include "../filesystem.h"  // dmlc::TemporaryDirectory
+#include "../helpers.h"
 
 namespace xgboost::common {
 TEST(MemoryFixSizeBuffer, Seek) {
@@ -89,6 +90,57 @@ TEST(IO, LoadSequentialFile) {
   ASSERT_THROW(LoadSequentialFile("non-exist", true), dmlc::Error);
 }
 
+TEST(IO, Resource) {
+  {
+    // test malloc basic
+    std::size_t n = 128;
+    std::shared_ptr<ResourceHandler> resource = std::make_shared<MallocResource>(n);
+    ASSERT_EQ(resource->Size(), n);
+    ASSERT_EQ(resource->Type(), ResourceHandler::kMalloc);
+  }
+
+  // test malloc resize
+  auto test_malloc_resize = [](bool force_malloc) {
+    std::size_t n = 64;
+    std::shared_ptr<ResourceHandler> resource = std::make_shared<MallocResource>(n);
+    auto ptr = reinterpret_cast<std::uint8_t *>(resource->Data());
+    std::iota(ptr, ptr + n, 0);
+
+    auto malloc_resource = std::dynamic_pointer_cast<MallocResource>(resource);
+    ASSERT_TRUE(malloc_resource);
+    if (force_malloc) {
+      malloc_resource->Resize<true>(n * 2);
+    } else {
+      malloc_resource->Resize<false>(n * 2);
+    }
+    for (std::size_t i = 0; i < n; ++i) {
+      ASSERT_EQ(malloc_resource->DataAs<std::uint8_t>()[i], i) << force_malloc;
+    }
+    for (std::size_t i = n; i < 2 * n; ++i) {
+      ASSERT_EQ(malloc_resource->DataAs<std::uint8_t>()[i], 0);
+    }
+  };
+  test_malloc_resize(true);
+  test_malloc_resize(false);
+
+  {
+    // test mmap
+    dmlc::TemporaryDirectory tmpdir;
+    auto path = tmpdir.path + "/testfile";
+
+    std::ofstream fout(path, std::ios::binary);
+    double val{1.0};
+    fout.write(reinterpret_cast<char const *>(&val), sizeof(val));
+    fout << 1.0 << std::endl;
+    fout.close();
+
+    auto resource = std::make_shared<MmapResource>(path, 0, sizeof(double));
+    ASSERT_EQ(resource->Size(), sizeof(double));
+    ASSERT_EQ(resource->Type(), ResourceHandler::kMmap);
+    ASSERT_EQ(resource->DataAs<double>()[0], val);
+  }
+}
+
 TEST(IO, PrivateMmapStream) {
   dmlc::TemporaryDirectory tempdir;
   auto path = tempdir.path + "/testfile";
@@ -124,17 +176,35 @@ TEST(IO, PrivateMmapStream) {
   // Turn size info offset
   std::partial_sum(offset.begin(), offset.end(), offset.begin());
 
+  // Test read
   for (std::size_t i = 0; i < n_batches; ++i) {
     std::size_t off = offset[i];
     std::size_t n = offset.at(i + 1) - offset[i];
-    std::unique_ptr<dmlc::Stream> fi{std::make_unique<PrivateMmapConstStream>(path, off, n)};
+    auto fi{std::make_unique<PrivateMmapConstStream>(path, off, n)};
     std::vector<T> data;
 
     std::uint64_t size{0};
-    fi->Read(&size);
+    ASSERT_TRUE(fi->Read(&size));
+    ASSERT_EQ(fi->Tell(), sizeof(size));
     data.resize(size);
 
-    fi->Read(data.data(), size * sizeof(T));
+    ASSERT_EQ(fi->Read(data.data(), size * sizeof(T)), size * sizeof(T));
+    ASSERT_EQ(data, batches[i]);
+  }
+
+  // Test consume
+  for (std::size_t i = 0; i < n_batches; ++i) {
+    std::size_t off = offset[i];
+    std::size_t n = offset.at(i + 1) - offset[i];
+    std::unique_ptr<AlignedResourceReadStream> fi{std::make_unique<PrivateMmapConstStream>(path, off, n)};
+    std::vector<T> data;
+
+    std::uint64_t size{0};
+    ASSERT_TRUE(fi->Consume(&size));
+    ASSERT_EQ(fi->Tell(), sizeof(size));
+    data.resize(size);
+
+    ASSERT_EQ(fi->Read(data.data(), size * sizeof(T)), sizeof(T) * size);
     ASSERT_EQ(data, batches[i]);
   }
 }