refactor: add enable_read_cache config to support disable read cache explicitly

Signed-off-by: zyy17 <zyylsxm@gmail.com>

config/config.md

@@ -103,6 +103,7 @@
 | `storage` | -- | -- | The data storage options. |
 | `storage.data_home` | String | `./greptimedb_data` | The working home directory. |
 | `storage.type` | String | `File` | The storage type used to store the data.<br/>- `File`: the data is stored in the local file system.<br/>- `S3`: the data is stored in the S3 object storage.<br/>- `Gcs`: the data is stored in the Google Cloud Storage.<br/>- `Azblob`: the data is stored in the Azure Blob Storage.<br/>- `Oss`: the data is stored in the Aliyun OSS. |
+| `storage.enable_read_cache` | Bool | `true` | Whether to enable read cache. If not set, the read cache will be enabled by default. |
 | `storage.cache_path` | String | Unset | Read cache configuration for object storage such as 'S3' etc, it's configured by default when using object storage. It is recommended to configure it when using object storage for better performance.<br/>A local file directory, defaults to `{data_home}`. An empty string means disabling. |
 | `storage.cache_capacity` | String | Unset | The local file cache capacity in bytes. If your disk space is sufficient, it is recommended to set it larger. |
 | `storage.bucket` | String | Unset | The S3 bucket name.<br/>**It's only used when the storage type is `S3`, `Oss` and `Gcs`**. |
@@ -494,6 +495,7 @@
 | `storage.data_home` | String | `./greptimedb_data` | The working home directory. |
 | `storage.type` | String | `File` | The storage type used to store the data.<br/>- `File`: the data is stored in the local file system.<br/>- `S3`: the data is stored in the S3 object storage.<br/>- `Gcs`: the data is stored in the Google Cloud Storage.<br/>- `Azblob`: the data is stored in the Azure Blob Storage.<br/>- `Oss`: the data is stored in the Aliyun OSS. |
 | `storage.cache_path` | String | Unset | Read cache configuration for object storage such as 'S3' etc, it's configured by default when using object storage. It is recommended to configure it when using object storage for better performance.<br/>A local file directory, defaults to `{data_home}`. An empty string means disabling. |
+| `storage.enable_read_cache` | Bool | `true` | Whether to enable read cache. If not set, the read cache will be enabled by default. |
 | `storage.cache_capacity` | String | Unset | The local file cache capacity in bytes. If your disk space is sufficient, it is recommended to set it larger. |
 | `storage.bucket` | String | Unset | The S3 bucket name.<br/>**It's only used when the storage type is `S3`, `Oss` and `Gcs`**. |
 | `storage.root` | String | Unset | The S3 data will be stored in the specified prefix, for example, `s3://${bucket}/${root}`.<br/>**It's only used when the storage type is `S3`, `Oss` and `Azblob`**. |

config/datanode.example.toml

@@ -274,6 +274,9 @@ type = "File"
 ## @toml2docs:none-default
 #+ cache_path = ""
 
+## Whether to enable read cache. If not set, the read cache will be enabled by default.
+enable_read_cache = true
+
 ## The local file cache capacity in bytes. If your disk space is sufficient, it is recommended to set it larger.
 ## @toml2docs:none-default
 cache_capacity = "5GiB"

config/standalone.example.toml

@@ -361,6 +361,9 @@ data_home = "./greptimedb_data"
 ## - `Oss`: the data is stored in the Aliyun OSS.
 type = "File"
 
+## Whether to enable read cache. If not set, the read cache will be enabled by default.
+enable_read_cache = true
+
 ## Read cache configuration for object storage such as 'S3' etc, it's configured by default when using object storage. It is recommended to configure it when using object storage for better performance.
 ## A local file directory, defaults to `{data_home}`. An empty string means disabling.
 ## @toml2docs:none-default

src/datanode/src/store.rs

@@ -87,6 +87,10 @@ async fn build_cache_layer(
     store_config: &ObjectStoreConfig,
     data_home: &str,
 ) -> Result<Option<LruCacheLayer<impl Access>>> {
+    if !store_config.enable_read_cache() {
+        return Ok(None);
+    }
+
     let (name, mut cache_path, cache_capacity) = match store_config {
         ObjectStoreConfig::S3(s3_config) => {
             let path = s3_config.cache.cache_path.clone();

src/object-store/src/config.rs

@@ -69,6 +69,19 @@ impl ObjectStoreConfig {
 
         name
     }
+
+    /// Returns whether to enable read cache. If not set, the read cache will be enabled by default.
+    pub fn enable_read_cache(&self) -> bool {
+        let enable_read_cache = match self {
+            Self::File(_) => Some(false),
+            Self::S3(s3) => s3.cache.enable_read_cache,
+            Self::Oss(oss) => oss.cache.enable_read_cache,
+            Self::Azblob(az) => az.cache.enable_read_cache,
+            Self::Gcs(gcs) => gcs.cache.enable_read_cache,
+        };
+
+        enable_read_cache.unwrap_or(true)
+    }
 }
 
 #[derive(Debug, Clone, Serialize, Default, Deserialize, Eq, PartialEq)]
@@ -304,6 +317,8 @@ impl Default for HttpClientConfig {
 #[derive(Debug, Clone, Serialize, Deserialize, Default, PartialEq)]
 #[serde(default)]
 pub struct ObjectStorageCacheConfig {
+    /// Whether to enable read cache. If not set, the read cache will be enabled by default.
+    pub enable_read_cache: Option<bool>,
     /// The local file cache directory
     pub cache_path: Option<String>,
     /// The cache capacity in bytes