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package com.jcabi.dynamo; |
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|
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import com.amazonaws.AmazonClientException; |
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import com.amazonaws.services.dynamodbv2.AmazonDynamoDB; |
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import com.amazonaws.services.dynamodbv2.model.AttributeValue; |
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import com.amazonaws.services.dynamodbv2.model.Condition; |
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import com.amazonaws.services.dynamodbv2.model.ReturnConsumedCapacity; |
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import com.amazonaws.services.dynamodbv2.model.ScanRequest; |
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import com.amazonaws.services.dynamodbv2.model.ScanResult; |
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import com.amazonaws.services.dynamodbv2.model.Select; |
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import com.google.common.collect.Iterables; |
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import com.jcabi.aspects.Immutable; |
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import com.jcabi.aspects.Loggable; |
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import com.jcabi.aspects.Tv; |
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import com.jcabi.log.Logger; |
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import java.io.IOException; |
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import java.util.ArrayList; |
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import java.util.Arrays; |
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import java.util.Collection; |
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import java.util.Collections; |
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import java.util.HashSet; |
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import java.util.List; |
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import java.util.Map; |
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import lombok.EqualsAndHashCode; |
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import lombok.ToString; |
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@Immutable |
64 | 4 | @ToString |
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@Loggable(Loggable.DEBUG) |
66 | 0 | @EqualsAndHashCode(of = { "limit", "attributes" }) |
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public final class ScanValve implements Valve { |
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private final transient int limit; |
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@Immutable.Array |
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private final transient String[] attributes; |
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public ScanValve() { |
84 | 5 | this(Tv.HUNDRED, new ArrayList<String>(0)); |
85 | 5 | } |
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92 | 5 | private ScanValve(final int lmt, final Iterable<String> attrs) { |
93 | 5 | this.limit = lmt; |
94 | 5 | this.attributes = Iterables.toArray(attrs, String.class); |
95 | 5 | } |
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|
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|
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@Override |
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public Dosage fetch(final Credentials credentials, |
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final String table, final Map<String, Condition> conditions, |
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final Collection<String> keys) throws IOException { |
102 | 2 | final AmazonDynamoDB aws = credentials.aws(); |
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try { |
104 | 1 | final Collection<String> attrs = new HashSet<String>( |
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Arrays.asList(this.attributes) |
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); |
107 | 1 | attrs.addAll(keys); |
108 | 1 | final ScanRequest request = new ScanRequest() |
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.withTableName(table) |
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.withAttributesToGet(attrs) |
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.withReturnConsumedCapacity(ReturnConsumedCapacity.TOTAL) |
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.withScanFilter(conditions) |
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.withLimit(this.limit); |
114 | 1 | final long start = System.currentTimeMillis(); |
115 | 1 | final ScanResult result = aws.scan(request); |
116 | 1 | Logger.info( |
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this, |
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"#items(): loaded %d item(s) from '%s' using %s, %s, in %[ms]s", |
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result.getCount(), table, conditions, |
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new PrintableConsumedCapacity( |
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result.getConsumedCapacity() |
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).print(), |
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System.currentTimeMillis() - start |
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); |
125 | 1 | return new ScanValve.NextDosage(credentials, request, result); |
126 | 0 | } catch (final AmazonClientException ex) { |
127 | 0 | throw new IOException( |
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String.format( |
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"failed to fetch from \"%s\" by %s and %s", |
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table, conditions, keys |
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), |
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ex |
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); |
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} finally { |
135 | 1 | aws.shutdown(); |
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} |
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} |
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|
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@Override |
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public int count(final Credentials credentials, final String table, |
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final Map<String, Condition> conditions) { |
142 | 0 | final AmazonDynamoDB aws = credentials.aws(); |
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try { |
144 | 0 | final ScanRequest request = new ScanRequest() |
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.withTableName(table) |
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.withReturnConsumedCapacity(ReturnConsumedCapacity.TOTAL) |
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.withScanFilter(conditions) |
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.withSelect(Select.COUNT) |
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.withLimit(Integer.MAX_VALUE); |
150 | 0 | final long start = System.currentTimeMillis(); |
151 | 0 | final ScanResult result = aws.scan(request); |
152 | 0 | final int count = result.getCount(); |
153 | 0 | Logger.info( |
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this, |
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|
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"#total(): COUNT=%d in '%s' using %s, %s, in %[ms]s", |
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count, request.getTableName(), request.getFilterExpression(), |
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new PrintableConsumedCapacity( |
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result.getConsumedCapacity() |
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).print(), |
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System.currentTimeMillis() - start |
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); |
163 | 0 | return count; |
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} finally { |
165 | 0 | aws.shutdown(); |
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} |
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} |
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public ScanValve withLimit(final int lmt) { |
175 | 0 | return new ScanValve(lmt, Arrays.asList(this.attributes)); |
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} |
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|
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|
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public ScanValve withAttributeToGet(final String name) { |
184 | 0 | return new ScanValve( |
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this.limit, |
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Iterables.concat( |
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Arrays.asList(this.attributes), |
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Collections.singletonList(name) |
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) |
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); |
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} |
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|
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public ScanValve withAttributeToGet(final String... names) { |
199 | 0 | return new ScanValve( |
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this.limit, |
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Iterables.concat( |
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Arrays.asList(this.attributes), |
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Arrays.asList(names) |
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) |
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); |
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} |
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|
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|
211 | 1 | @ToString |
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@Loggable(Loggable.DEBUG) |
213 | 0 | @EqualsAndHashCode(of = { "credentials", "request", "result" }) |
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private final class NextDosage implements Dosage { |
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private final transient Credentials credentials; |
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private final transient ScanRequest request; |
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private final transient ScanResult result; |
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NextDosage(final Credentials creds, final ScanRequest rqst, |
234 | 1 | final ScanResult rslt) { |
235 | 1 | this.credentials = creds; |
236 | 1 | this.request = rqst; |
237 | 1 | this.result = rslt; |
238 | 1 | } |
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@Override |
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public List<Map<String, AttributeValue>> items() { |
241 | 2 | return this.result.getItems(); |
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} |
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@Override |
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public boolean hasNext() { |
245 | 2 | return this.result.getLastEvaluatedKey() != null; |
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} |
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@Override |
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public Dosage next() { |
249 | 0 | if (!this.hasNext()) { |
250 | 0 | throw new IllegalStateException( |
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"nothing left in the iterator" |
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); |
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} |
254 | 0 | final AmazonDynamoDB aws = this.credentials.aws(); |
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try { |
256 | 0 | final ScanRequest rqst = this.request.withExclusiveStartKey( |
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this.result.getLastEvaluatedKey() |
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); |
259 | 0 | final long start = System.currentTimeMillis(); |
260 | 0 | final ScanResult rslt = aws.scan(rqst); |
261 | 0 | Logger.info( |
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this, |
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|
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"#next(): loaded %d item(s) from '%s' using %s, %s, in %[ms]s", |
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rslt.getCount(), rqst.getTableName(), rqst.getScanFilter(), |
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new PrintableConsumedCapacity( |
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rslt.getConsumedCapacity() |
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).print(), |
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System.currentTimeMillis() - start |
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); |
271 | 0 | return new ScanValve.NextDosage(this.credentials, rqst, rslt); |
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} finally { |
273 | 0 | aws.shutdown(); |
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} |
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} |
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} |
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} |